Quantum vortex dynamics in two-dimensional neutral superfluids (2009)
Wang, C. -C. Joseph, Duine, R. A., MacDonald, A. H.
We derive an effective action for the vortex position degree-of-freedom in a superfluid by integrating out condensate phase and density fluctuation environmental modes. When the quantum dynamics of...
Anomalous Exciton-Condensation in Graphene Bilayers (2009)
Barlas, Yafis, Côté, Rene, Lambert, J., MacDonald, A. H.
In ordinary semiconductor bilayers, exciton condensates appear at total Landau level filling factor $\nu_{T}=1$. We predict that similar states will occur in Bernal stacked graphene bilayers at many...
Theory of the Magnetic-Field-Induced Insulator in Neutral Graphene (2009)
Recent experiments have demonstrated that neutral graphene sheets have an insulating ground state in the presence of an external magnetic field. We report on a $\pi$-band tight-binding-model...
Blockade and superdrag in exciton-condensate Josephson junctions (2009)
Dolcini, Fabrizio, Rainis, Diego, Taddei, Fabio, Polini, Marco, Fazio, Rosario, MacDonald, A. H.
Boson and Fermion-pair condensation are the most remarkable phenomena in statistical physics because they promote quantum behaviour from the microscopic to the macroscopic world. In this Letter we...
Drude-Interband Coupling, Screening, and the Optical Conductivity of Doped Bilayer Graphene (2009)
Tse, Wang-Kong, MacDonald, A. H.
We present a theory of the influence of band renormalization and excitonic electron-electron interaction effects on the optical conductivity $\sigma(\omega)$ of doped bilayer graphene. Using the...
Magnetic properties of substitutional Mn in (110) GaAs surface and subsurface layers (2009)
Strandberg, T. O., Canali, C. M., MacDonald, A. H.
Motivated by recent STM experiments, we present a theoretical study of the electronic and magnetic properties of the Mn-induced acceptor level obtained by substituting a single Ga atom in the (110)...
Influence of a uniform current on collective magnetization dynamics in a ferromagnetic metal (2009)
Braun, M., Fernandez-Rossier, J., Nunez, A. S., MacDonald, A. H.
Electron-electron interactions in graphene bilayers (2009)
Zhang, Fan, Min, Hongki, Polini, Marco, MacDonald, A. H.
Electrons most often organize into Fermi-liquid states in which electron-electron interactions play an inessential role. A well known exception is the case of one-dimensional (1D) electron systems...
Hydrodynamic theory of transport in doped graphene (2009)
Bistritzer, R., MacDonald, A. H.
We study non-linear dc transport in graphene using a hydrodynamic approach and conclude that in clean samples the drift velocity saturates at a weakly density-dependent value v_{sat} ~ 10^7 cm/s. We...
Theory of Interedge Superexchange in Zigzag Edge Magnetism (2009)
Jung, J., Pereg-Barnea, T., MacDonald, A. H.
A graphene nanoribbon with zigzag edges has a gapped magnetic ground state with an antiferromagnetic interedge superexchange interaction. We present a theory based on asymptotic properties of the...
Dynamical response functions and collective modes of bilayer graphene (2009)
Borghi, Giovanni, Polini, Marco, Asgari, Reza, MacDonald, A. H.
Bilayer graphene (BLG) has recently attracted a great deal of attention because of its electrically tunable energy gaps and its unusual electronic structure. In this Letter we present analytical and...
Spin-Orbit Interactions in Bilayer Exciton-Condensate Ferromagnets (2009)
Bilayer electron-hole systems with unequal electron and hole densities are expected to have exciton condensate ground states with spontaneous spin-polarization in both conduction and valence bands....
Berry Phase Coupling and the Cuprate Neutron Scattering Resonance (2009)
Lee, Wei-Cheng, MacDonald, A. H.
We examine the influence of coupling between particle-hole and particle-particle spin fluctuations on the inelastic neutron scattering resonance (INSR) in cuprate superconductors in both weak and...
Nagaosa, Naoto, Sinova, Jairo, Onoda, Shigeki, MacDonald, A. H., Ong, N. P.
We present a review of experimental and theoretical studies of the anomalous Hall effect (AHE), focusing on recent developments that have provided a more complete framework for understanding this...
Carrier Density and Magnetism in Graphene Zigzag Nanoribbons (2009)
The influence of carrier density on magnetism in a zigzag graphene nanoribbon is studied in a $\pi$-orbital Hubbard-model mean-field approximation. Departures from half-filling alter the magnetism,...
Fermi velocity enhancement in monolayer and bilayer graphene (2009)
Borghi, Giovanni, Polini, Marco, Asgari, Reza, MacDonald, A.H.
In single-layer graphene sheets non-local interband exchange leads to a renormalized Fermi-surface effective mass which vanishes in the low carrier-density limit. We report on a comparative study of...
Universal Interband Conductivity in Graphene Multilayers (2009)
We predict that the optical conductivity of normal graphene multilayers is close to $\sigma_{uni}=(\pi/2) e^2/h$ per layer over a broad range of frequencies. The origin of this behavior is an...
Fermi Velocity Enhancement in Monolayer and Bilayer Graphene (2009)
Borghi, Giovanni, Polini, Marco, Asgari, Reza, MacDonald, A. H.
In single-layer graphene sheets non-local interband exchange leads to a renormalized Fermi-surface effective mass which vanishes in the low carrier-density limit. We report on a comparative study of...
Drude weight, plasmon dispersion, and pseudospin response in doped graphene sheets (2009)
Polini, Marco, MacDonald, A. H., Vignale, G.
Plasmons in ordinary electron liquids are collective excitations whose long-wavelength limit is rigid center-of-mass motion with a dispersion relation that is, as a consequence of Galileian...
Electronic Cooling in Graphene (2009)
Bistritzer, R., MacDonald, A. H.
Energy transfer to acoustic phonons is the dominant low-temperature cooling channel of electrons in a crystal.For cold neutral graphene we find that the weak cooling power of its acoustical modes...
Non-Adiabatic Spin Transfer Torque in Real Materials (2008)
Garate, Ion, Gilmore, K., Stiles, M. D., MacDonald, A. H.
The motion of simple domain walls and of more complex magnetic textures in the presence of a transport current is described by the Landau-Lifshitz-Slonczewski (LLS) equations. Predictions of the LLS...
Theory of inter-edge superexchange in zigzag edge magnetism (2008)
Jung, J., Pereg-Barnea, T., MacDonald, A. H.
A graphene nanoribbon with zigzag edges has a gapped magnetic ground state with an antiferromagnetic inter-edge superexchange interaction. We present a theory based on asymptotic properties of the...
Theory of Weak Localization in Ferromagnetic (Ga,Mn)As (2008)
Garate, Ion, Sinova, Jairo, Jungwirth, T., MacDonald, A. H.
We study quantum interference corrections to the conductivity in (Ga,Mn)As ferromagnetic semiconductors using a model with disordered valence band holes coupled to localized Mn moments through a p-d...
Finite-temperature Screening and the Specific Heat of Doped Graphene Sheets (2008)
Ramezanali, M. R., Vazifeh, M. M., Asgari, Reza, Polini, Marco, MacDonald, A. H.
At low energies, electrons in doped graphene sheets are described by a massless Dirac fermion Hamiltonian. In this work we present a semi-analytical expression for the dynamical density-density...
Comment on "Electron screening and excitonic condensation in double-layer graphene systems" (2008)
Bistritzer, R., Min, H., Su, J. J., MacDonald, A. H.
The influence of screening on the condensed state of bilayer graphene is studied within the framework of the Thomas Fermi approximation. We find that screening has little effect on the...
Influence of Disorder on Electron-Hole Pair Condensation in Graphene Bilayers (2008)
Bistritzer, R., MacDonald, A. H.
Graphene bilayers can condense into a state with spontaneous interlayer phase coherence that supports dissipationless counterflow supercurrents. Here we address the influence of disorder on the...
Electronic structure of multilayer graphene (2008)
We study the electronic structure of multilayer graphene using a $\pi$-orbital continuum model with nearest-neighbor intralayer and interlayer tunneling. Using degenerate state perturbation theory,...
ARPES, Neutrons, and the High-$T_c$ Mechanism (2008)
Lee, Wei-Cheng, MacDonald, A. H.
Extensive ARPES and low-energy inelastic neutron scattering studies of cuprate superconductors can be successfully described using a weak-coupling theory in which quasiparticles on a square lattice...
Chern-number spin Hamiltonians for magnetic nano-clusters by DFT methods (2008)
Strandberg, T. O., Canali, C. M., MacDonald, A. H.
Combining field-theoretical methods and ab-initio calculations, we construct an effective Hamiltonian with a single giant-spin degree of freedom, capable of the describing the low-energy spin...
Density-Functional Theory of Graphene Sheets (2008)
Polini, Marco, Tomadin, Andrea, Asgari, Reza, MacDonald, A. H.
We outline a Kohn-Sham-Dirac density-functional-theory (DFT) scheme for graphene sheets that treats slowly-varying inhomogeneous external potentials and electron-electron interactions on an equal...
Theory of Graphene Chiral Quasiparticle LDOS maps (2008)
Pereg-Barnea, T., MacDonald, A. H.
We present a theory of momentum space local density-of-states (LDOS) maps N(q,omega) in graphene. The LDOS map has both intravalley contributions centered near zero momentum and reciprocal lattice...
Intra-Landau level Cyclotron Resonance in Bilayer Graphene (2008)
Barlas, Yafis, Cote, R., Nomura, K., MacDonald, A. H.
Interaction driven integer quantum Hall effects are anticipated in graphene bilayers because of the near-degeneracy of the eight Landau levels which appear near the neutral system Fermi level. We...
Room-Temperature Superfluidity in Graphene Bilayers (2008)
Min, Hongki, Bistritzer, Rafi, Su, Jung-Jung, MacDonald, A. H.
Because graphene is an atomically two-dimensional gapless semiconductor with nearly identical conduction and valence bands, graphene-based bilayers are attractive candidates for high-temperature...
How to make a bilayer exciton condensate flow (2008)
Su, Jung-Jung, MacDonald, A. H.
Bose condensation is responsible for many of the most spectacular effects in physics because it can promote quantum behavior from the microscopic to the macroscopic world. Bose condensates can be...
Current-induced torques in magnetic metals: beyond spin transfer (2008)
Haney, P.M., Duine, R.A., Núñez, A.S., MacDonald, A.H.
Current-induced torques on ferromagnetic nanoparticles and on domain walls in ferromagnetic nanowires are normally understood in terms of transfer of conserved spin angular momentum between...
Hysteretic behavior in weakly coupled double-dot transport in the spin blockade regime (2007)
Inarrea, J., Lopez-Monis, C., MacDonald, A. H., Platero, G.
Double quantum dot systems in the spin blockade regime exhibit leakage currents that have been attributed to the Hyperfine interaction. We model weakly coupled double-dot transport using a rate...
Basu, D., Gilbert, M. J., Register, L. F., MacDonald, A. H., Banerjee, S. K.
Results of quantum mechanical simulations of the influence of edge disorder on transport in graphene nanoribbon metal oxide semiconductor field-effect transistors (MOSFETs) are reported. The addition...
Anomalous Hall effect in a two-dimensional electron gas (2007)
Nunner, Tamara S., Sinitsyn, N. A., Borunda, Mario F., Dugaev, V. K., Kovalev, A. A., Abanov, Ar., ...
The anomalous Hall effect in a magnetic two-dimensional electron gas with Rashba spin-orbit coupling is studied within the Kubo-Streda formalism in the presence of pointlike potential impurities. We...
Chiral Decomposition in the Electronic Structure of Graphene Multilayers (2007)
We show that the low-energy electronic structure of arbitrarily stacked graphene multilayers with nearest-neighbor interlayer tunneling consists of chiral pseudospin doublets. Although the number of...
Lee, Wei-Cheng, Sinova, Jairo, Burkov, A. A., Joglekar, Yogesh, MacDonald, A. H.
The critical temperature of an underdoped cuprate superconductor is limited by its phase stiffness $\rho$. In this Letter we argue that the dependence of $\rho$ on doping $x$ should be understood as...
Electronic correlations and disorder in transport through one-dimensional nanoparticle arrays (2007)
Bascones, E., Estevez, V., Trinidad, J. A., MacDonald, A. H.
We analyze and clarify the transport properties of a one-dimensional metallic nanoparticle array with interaction between charges restricted to charges placed in the same conductor. We study the...
Effect of the long-range interaction in transport through one-dimensional nanoparticle arrays (2007)
Bascones, E., Trinidad, J. A., Estevez, V., MacDonald, A. H.
We analyze the effect of the long-range interaction on the transport properties through ordered and disordered one-dimensional metallic nanoparticle arrays. We discuss how the threshold voltage, the...
Current-Induced Torques in Magnetic Metals: Beyond Spin Transfer (2007)
Haney, P. M., Duine, R. A., Nunez, A. S., MacDonald, A. H.
Current-induced torques on ferromagnetic nanoparticles and on domain walls in ferromagnetic nanowires are normally understood in terms of transfer of conserved spin angular momentum between...
The Role of Electron-electron Interactions in Graphene ARPES Spectra (2007)
Polini, Marco, Asgari, Reza, Borghi, Giovanni, Barlas, Yafis, Pereg-Barnea, T., MacDonald, A. H.
We report on a theoretical study of the influence of electron-electron interactions on ARPES spectra in graphene that is based on the random-phase-approximation and on graphene's massless Dirac...
Theory of the Pseudospin Resonance in Semiconductor Bilayers (2007)
Abedinpour, Saeed H., Polini, Marco, MacDonald, A. H., Tanatar, B., Tosi, M. P., Vignale, G.
The pseudospin degree of freedom in a semiconductor bilayer gives rise to a collective mode analogous to the ferromagnetic resonance mode of a ferromagnet. We present a theory of the dependence of...
Graphene: A Pseudochiral Fermi Liquid (2007)
Polini, Marco, Asgari, Reza, Barlas, Yafis, Pereg-Barnea, T., MacDonald, A. H.
Doped graphene sheets are pseudochiral two-dimensional Fermi liquids with abnormal electron-electron interaction physics. We address graphene's Fermi liquid properties quantitatively using a...
Functional Keldysh Theory of Spin Torques (2007)
Duine, R. A., Nunez, A. S., Sinova, Jairo, MacDonald, A. H.
We present a microscopic treatment of current-induced torques and thermal fluctuations in itinerant ferromagnets based on a functional formulation of the Keldysh formalism. We find that the...
Optical Control of Topological Quantum Transport in Semiconductors (2007)
Yao, Wang, MacDonald, A. H., Niu, Qian
Intense coherent laser radiation red-detuned from absorption edge can reactively activate sizable Hall type charge and spin transport in n-doped paramagnetic semiconductors as a consequence of...
Ab-initio GMR and current-induced torques in Au/Cr multilayers (2006)
Haney, P. M., Waldron, D., Duine, R. A., Nunez, A. S., Guo, H., MacDonald, A. H.
We report on an {\em ab-initio} study of giant magnetoresistance (GMR) and current-induced-torques (CITs) in Cr/Au multilayers that is based on non-equilibrium Green's functions and spin density...
Current Induced Order Parameter Dynamics: Microscopic Theory Applied to Co/Cu/Co spin valves (2006)
Haney, P. M., Waldron, D., Duine, R. A., Nunez, A. S., Guo, H., MacDonald, A. H.
Transport currents can alter alter order parameter dynamics and change steady states in superconductors, in ferromagnets, and in hybrid systems. In this article we present a scheme for fully...
Inelastic scattering in ferromagnetic and antiferromagnetic metal spintronics (2006)
Duine, R. A., Haney, P. M., Nunez, A. S., MacDonald, A. H.
We use a ferromagnetic voltage probe model to study the influence of inelastic scattering on giant magnetoresistance and current-induced torques in ferromagnetic and antiferromagnetic metal spin...
Inarrea, Jesus, Platero, Gloria, MacDonald, A. H.
We analyzed the electronic transport through a double quantum dot in the spin blockade regime. Experiments of current rectification by Pauli exclusion principle in double quantum dots were discussed....
Sinitsyn, N. A., MacDonald, A. H., Jungwirth, T., Dugaev, V. K., Sinova, Jairo
The anomalous Hall effect (AHE) is a consequence of spin-orbit coupling in a ferromagnetic metal and is related primarily to density-matrix response to an electric field that is off-diagonal in band...
Quantum transport of massless Dirac fermions in graphene (2006)
Nomura, Kentaro, MacDonald, A. H.
Motivated by recent graphene transport experiments, we have undertaken a numerical study of the conductivity of disordered two-dimensional massless Dirac fermions. Our results reveal distinct...
Intrinsic and Rashba Spin-orbit Interactions in Graphene Sheets (2006)
Min, Hongki, Hill, J. E., Sinitsyn, N. A., Sahu, B. R., Kleinman, Leonard, MacDonald, A. H.
Starting from a microscopic tight-binding model and using second order perturbation theory, we derive explicit expressions for the intrinsic and Rashba spin-orbit interaction induced gaps in the...
Collective Modes and Skyrmion Excitations in Graphene SU(4) Quantum Hall Ferromagnets (2006)
Yang, Kun, Sarma, S. Das, MacDonald, A. H.
Graphene exhibits quantum Hall ferromagnetism in which an approximate SU(4) symmetry involving spin and valley degrees of freedom is spontaneously broken. We construct a set of integer and fractional...
Quantum Hall Ferromagnetism in Graphene (2006)
Nomura, Kentaro, MacDonald, A. H.
Graphene is a two-dimensional carbon material with a honeycomb lattice and Dirac-like low-energy excitations. When Zeeman and spin-orbit interactions are neglected its Landau levels are four-fold...
Charge and spin Hall conductivity in metallic graphene (2006)
Sinitsyn, N. A., Hill, J. E., Min, Hongki, Sinova, Jairo, MacDonald, A. H.
Graphene has an unusual low-energy band structure with four chiral bands and half-quantized and quantized Hall effects that have recently attracted theoretical and experimental attention. We study...
Magnetic Anisotropy of Isolated Cobalt Nanoplatelets (2005)
Strandberg, T. O., Canali, C. M., MacDonald, A. H.
Motivated in part by experiments performed by M.H. Pan et al. (nanoletters, v.5, p 83, 2005), we have undertaken a theoretical study of the the magnetic properties of two-monolayer thick Co...
Coordinate shift in the semiclassical Boltzmann equation and the anomalous Hall effect (2005)
Sinitsyn, N. A., Niu, Q., MacDonald, A. H.
We propose a gauge invariant expression for the side jump associated with scattering between particular Bloch states. Our expression for the side jump follows from the Born series expansion for the...
Antiferromagnetic Metal Spintronics (2005)
Nunez, A. S., Duine, R. A., MacDonald, A. H.
Spintronics in ferromagnetic metals is built on a complementary set of phenomena in which magnetic configurations influence transport coefficients and transport currents alter magnetic...
Interlayer Transport in Bilayer Quantum Hall Systems (2005)
Rossi, Enrico, Núñez, Alvaro S., MacDonald, A. H.
Bilayer quantum Hall systems have a broken symmetry ground state at filling factor $\nu=1$ which can be viewed either as an excitonic superfluid or as a pseudospin ferromagnet. We present a theory of...
Edge spin accumulation in semiconductor two-dimensional hole gases (2005)
Nomura, K., Wunderlich, J., Sinova, Jairo, Kaestner, B., MacDonald, A. H., Jungwirth, T.
The controlled generation of localized spin densities is a key enabler of semiconductor spintronics In this work, we study spin Hall effect induced edge spin accumulation in a two-dimensional hole...
Edge Magnetoplasmons in Quantum Hall Line Junction Systems (2005)
Lee, Wei-Cheng, Sinitsyn, N. A., Papa, Emiliano, MacDonald, A. H.
A quantum Hall line junction system consists of a one-dimensional Luttinger liquid (LL) and two chiral channels that allow density waves incident upon and reflected by the LL to be measured...
Dependence of the intrinsic spin Hall effect on spin-orbit interaction character (2005)
Nomura, K., Sinova, Jairo, Sinitsyn, N. A., MacDonald, A. H.
We report on a comparative numerical study of the spin Hall conductivity in two-dimensions for three different spin-orbit interaction models; the standard k-linear Rashba model, the k-cubic Rashba...
Dynamics of magnetization coupled to a thermal bath of elastic modes (2005)
Rossi, Enrico, Heinonen, Olle G., MacDonald, A. H.
We study the dynamics of magnetization coupled to a thermal bath of elastic modes using a system plus reservoir approach with realistic magnetoelastic coupling. After integrating out the elastic...
Ganguly, Swaroop, MacDonald, A. H., Register, L. F., Banerjee, S.
We predict bistability in the Curie temperature-voltage characteristic of double barrier resonant-tunneling structures with dilute ferromagnetic semiconductor quantum wells. Our conclusions are based...
Fully Frustrated Cold Atoms (2005)
Polini, Marco, Fazio, Rosario, MacDonald, A. H., Tosi, M. P.
Fully frustrated Josephson Junction arrays (FF-JJA's) exhibit a subtle compound phase transition in which an Ising transition associated with discrete broken translational symmetry and a...
Ganguly, Swaroop, Register, L. F., Banerjee, S., MacDonald, A. H.
We predict that the Curie temperature of a ferromagnetic resonant tunneling diode will decrease abruptly, by approximately a factor of two, when the downstream chemical potential falls below the...
Non-vanishing spin Hall currents in disordered spin-orbit coupling systems (2004)
Nomura, K., Sinova, Jairo, Jungwirth, T., Niu, Q., MacDonald, A. H.
Spin currents that flow perpendicular to the electric field direction are generic in metals and doped semiconductors with spin-orbit coupling. It has recently been argued that the spin Hall...
Wang, Q. Q., Muller, A., Bianucci, P., Rossi, E., Xue, Q. K., Takagahara, T., ...
Using photoluminescence spectroscopy, we have investigated the nature of Rabi oscillation damping during active manipulation of excitonic qubits in self-assembled quantum dots. Rabi oscillations were...
Bose-Einstein Condensation of Excitons in Bilayer Electron Systems (2004)
Eisenstein, J. P., MacDonald, A. H.
An ordered state of electrons in solids in which excitons condense was proposed many years ago as a theoretical possibility but has, until recently, never been observed. We review recent studies of...
Spin Transfer Without Spin Conservation (2004)
Núñez, Alvaro S., MacDonald, A. H.
We propose a general theory of the spin-transfer effects that occur when current flows through inhomogeneous magnetic systems. Our theory does not rest on an appeal to conservation of total spin, can...
Coherently photo-induced ferromagnetism in diluted magnetic semiconductors (2003)
Fernández-Rossier, J., Piermarocchi, C., Chen, P., MacDonald, A. H., Sham, L. J.
Ferromagnetism is predicted in undoped diluted magnetic semiconductors illuminated by intense sub-bandgap laser radiation . The mechanism for photo-induced ferromagnetism is coherence between...
Orbital and spin contributions to the $g$-tensors in metal nanoparticles (2003)
Cehovin, A., Canali, C. M., MacDonald, A. H.
We present a theoretical study of the mesoscopic fluctuations of $g$-tensors in a metal nanoparticle. The calculations were performed using a semi-realistic tight-binding model, which contains both...
Burkov, A. A., Nunez, Alvaro S., MacDonald, A. H.
We use microscopic linear response theory to derive a set of equations that provide a complete description of coupled spin and charge diffusive transport in a two-dimensional electron gas (2DEG) with...
Semiclassical theory of spin transport in spin-orbit coupled systems (2003)
Culcer, Dimitrie, Sinova, Jairo, Sinitsyn, N. A., Jungwirth, T., MacDonald, A. H., Niu, Q.
Motivated by recent interest in novel spintronics effects, we develop a semiclassical theory of spin transport that is valid for spin-orbit coupled bands. Aside from the obvious convective term in...
Magnetization relaxation in (Ga,Mn)As ferromagnetic semiconductors (2003)
Sinova, Jairo, Jungwirth, T., Liu, X., Sasaki, Y., Furdyna, J. K., Atkinson, W. A., ...
We describe a theory of Mn local-moment magnetization relaxation due to p-d kinetic-exchange coupling with the itinerant-spin subsystem in the ferromagnetic semiconductor (Ga,Mn)As alloy. The...
Numerical Investigation on Asymmetric Bilayer System at Integer Filling Factor (2003)
Nomura, K., Yoshioka, D., Jungwirth, T., MacDonald, A. H.
Deformation of the easy-axis ferromagnetic state in asymmetric bilayer systems are investigated numerically. Using the exact diagonalization the easy-axis to easy-plane ferromagnetic transition at...
Universal Intrinsic Spin-Hall Effect (2003)
Sinova, Jairo, Culcer, Dimitrie, Niu, Q., Sinitsyn, N. A., Jungwirth, T., MacDonald, A. H.
We describe a new effect in semiconductor spintronics that leads to dissipationless spin-currents in paramagnetic spin-orbit coupled systems. We argue that in a high mobility two-dimensional electron...
First Principles Calculation of Anomalous Hall Conductivity in Ferromagnetic bcc Fe (2003)
Yao, Yugui, Kleinman, L., MacDonald, A. H., Sinova, Jairo, Jungwirth, T., Wang, Ding-sheng, ...
We perform a first principles calculation of the anomalous Hall effect in ferromagnetic bcc Fe. Our theory identifies an intrinsic contribution to the anomalous Hall conductivity and relates it to...
Tunneling exponents in realistic quantum wires using the mean field approximation (2003)
Häusler, Wolfgang, MacDonald, A. H.
It is demonstrated that the charge Tomonaga-Luttinger parameter $K_\rho$ of quantum wires can be estimated accurately using the Hartree-Fock approximation if carried out self consistently. The...
Critical Currents of Ideal Quantum Hall Superfluids (2003)
Abolfath, M., MacDonald, A. H., Radzihovsky, L.
Filling factor $\nu=1$ bilayer electron systems in the quantum Hall regime have an excitonic-condensate superfluid ground state when the layer separation $d$ is less than a critical value $d_c$. On a...
Optical spin transfer in ferromagnetic semiconductors (2003)
Fernández-Rossier, J., Núñez, Alvaro S., Abolfath, M., MacDonald, A. H.
Circularly polarized laser pulses that excite electron-hole pairs across the band gap of (III,Mn)V ferromagnetic semiconductors can be used to manipulate and to study collective magnetization...
Elementary Excitations of Ferromagnetic Metal Nanoparticles (2003)
Cehovin, A., Canali, C. M., MacDonald, A. H.
We present a theory of the elementary spin excitations in transition metal ferromagnet nanoparticles which achieves a unified and consistent quantum description of both collective and quasiparticle...
Chern Numbers for Spin Models of Transition Metal Nanomagnets (2003)
Canali, C. M., Cehovin, A., MacDonald, A. H.
We argue that ferromagnetic transition metal nanoparticles with fewer than approximately 100 atoms can be described by an effective Hamiltonian with a single giant spin degree of freedom. The total...
Rezayi, E. H., Jungwirth, T., MacDonald, A. H., Haldane, F. D. M.
Opposite spin Landau levels in a quantum well can be brought into coincidence by tilting the magnetic field away from normal orientation. We demonstrate that the magnetotransport anomaly at integer...
DC-transport properties of ferromagnetic (Ga,Mn)As semiconductors (2003)
Jungwirth, T., Sinova, Jairo, Wang, K. Y., Edmonds, K. W., Campion, R. P., Gallagher, B. L., ...
We study the dc transport properties of (Ga,Mn)As diluted magnetic semiconductors with Mn concentration varying from 1.5% to 8%. Both diagonal and Hall components of the conductivity tensor are...
Infrared magneto-optical properties of (III,Mn)V ferromagetic semiconductors (2003)
Sinova, Jairo, Jungwirth, T., Kucera, J., MacDonald, A. H.
We present a theoretical study of the infrared magneto-optical properties of ferromagnetic (III,Mn)V semiconductors. Our analysis combines the kinetic exchange model for (III,Mn)V ferromagnetism with...
Fractional-quantum-Hall edge electrons and Fermi statistics (2003)
Zuelicke, U., Palacios, J. J., MacDonald, A. H.
We address the quantum statistics of electrons created in the low-energy edge-state Hilbert space sector of incompressible fractional quantum Hall states, considering the possibility that they may...
Momentum Distribution Function of a Narrow Hall Bar in the FQHE Regime (2002)
Yang, S. -R. Eric, Mitra, Sami, Fisher, M. P. A., MacDonald, A. H.
The momentum distribution function ($n(k)$) of a narrow Hall bar in the fractional quantum Hall effect regime is investigated using Luttinger liquid and microscopic many-particle wavefunction...
Theoretical models of ferromagnetic III-V semiconductors (2002)
Jungwirth, T., Sinova, Jairo, Kučera, J., MacDonald, A. H.
Recent materials research has advanced the maximum ferromagnetic transition temperature in semiconductors containing magnetic elements toward room temperature. Reaching this goal would make...
Non-Drude Optical Conductivity of (III,Mn)V Ferromagnetic Semiconductors (2002)
Yang, S. -R. Eric, Sinova, Jairo, Jungwirth, T., Shim, Y. P., MacDonald, A. H.
We present a numerical model study of the zero-temperature infrared optical properties of (III,Mn)V diluted magnetic semiconductors. Our calculations demonstrate the importance of treating disorder...
Boltzmann theory of engineered anisotropic magnetoresistance in (Ga,Mn)As (2002)
Jungwirth, T., Abolfath, M., Sinova, Jairo, Kucera, J., MacDonald, A. H.
We report on a theoretical study of dc transport coefficients in (Ga,Mn)As diluted magnetic semiconductor ferromagnets that accounts for quasiparticle scattering from ionized Mn$^{2+}$ acceptors with...
Electron-Phonon Interactions in Polyacene Organic Transistors (2002)
Sinova, Jairo, Núñez, Alvaro, Schliemann, John, MacDonald, A. H.
We present a simple model for the electron-phonon interactions between the energy subbands in polyacene field-effect transistors and the vibrations of the crystal. We introduce a generalized...
Sinova, Jairo, MacDonald, A. H., Girvin, S. M.
We present a Hartree-Fock study of the competition between disorder and interactions in quantum Hall ferromagnets near $\nu=1$. We find that the ground state at $\nu=1$ evolves with increasing...
Infrared conductivity of metallic (III,Mn)V ferromagnets (2002)
Sinova, Jairo, Jungwirth, T., Yang, S. - R. Eric, Kučera, J., MacDonald, A. H.
We present a theory of the infrared conductivity and absorption coefficients of metallic (III,Mn)V ferromagnetic semiconductors. We find that the conductivity is dominated by inter-valence-band...
Ferromagnetism in Diluted Magnetic Semiconductor Heterojunction Systems (2002)
Lee, Byounghak, Jungwirth, T., MacDonald, A. H.
Diluted magnetic semiconductors (DMSs), in which magnetic elements are substituted for a small fraction of host elements in a semiconductor lattice, can become ferromagnetic when doped. In this...
Coupling between Edge and Bulk in Strong-Field Quantum Dots (2002)
Yang, S. -R. Eric, MacDonald, A. H.
The maximum-density-droplet (MDD) state of quantum-dot electrons becomes unstable at strong magnetic fields to the addition of interior holes. Using exact diagonalization, we demonstrate that the...
$\nu=2$ Bilayer Quantum Hall System in Tilted Magnetic Field (2002)
Burkov, A. A., MacDonald, A. H.
We report on a theoretical study of $\nu=2$ bilayer quantum Hall systems with a magnetic field that has a component parallel to the layers. As in the $\nu=1$ case, interlayer phase coherence is...
Lattice Pseudospin Model for $\nu=1$ Quantum Hall Bilayers (2002)
Burkov, A. A., MacDonald, A. H.
We present a new theoretical approach to the study of $\nu=1$ quantum Hall bilayer that is based on a systematic mapping of the microscopic Hamiltonian to an anisotropic SU(4) spin model on a...
Curie Temperature Trends in (III,Mn)V Ferromagnetic Semiconductors (2002)
Jungwirth, T., König, Jürgen, Sinova, Jairo, Kučera, J., MacDonald, A. H.
We present a theoretical survey of ferromagnetic transition temperatures in cubic (III,Mn)V semiconductors based on a model with $S=5/2$ local moments exchange-coupled to itinerant holes in the host...
Broken-Symmetry States in Quantum Hall Superlattices (2001)
Hanna, C. B., Diaz-Velez, J. C., MacDonald, A. H.
We argue that broken-symmetry states with either spatially diagonal or spatially off-diagonal order are likely in the quantum Hall regime, for clean multiple quantum well (MQW) systems with small...
Theory of Ferromagnetism in Doped Excitonic Condensates (2001)
Bascones, E., Burkov, A. A., MacDonald, A. H.
Nesting in a semimetal can lead to an excitonic insulator state with spontaneous coherence between conduction and valence bands and a gap for charged excitations. In this paper we present a theory of...
Ferromagnetism in (III,Mn)V Semiconductors (2001)
König, J., Schliemann, J., Jungwirth, T., MacDonald, A. H.
In this review article we briefly summarize the main experimental properties of (III,Mn)V ferromagnets and outline several different but related approaches that have been explored in an effort to...
Anomalous Hall effect in ferromagnetic semiconductors (2001)
Jungwirth, T., Niu, Qian, MacDonald, A. H.
We present a theory of the anomalous Hall effect in ferromagnetic (Mn,III)V semiconductors. Our theory relates the anomalous Hall conductance of a homogeneous ferromagnet to the Berry phase acquired...
Quantum-Hall Quantum-Bits (2001)
Yang, S. -R. Eric, Schliemann, John, MacDonald, A. H.
Bilayer quantum Hall systems can form collective states in which electrons exhibit spontaneous interlayer phase coherence. We discuss the possibility of using bilayer quantum dot many-electron states...
Global phase diagram of bilayer quantum Hall ferromagnets (2001)
Abolfath, M., Radzihovsky, L., MacDonald, A. H.
We present a microscopic study of the interlayer spacing d versus in-plane magnetic field $B_\parallel$ phase diagram for bilayer quantum Hall (QH) pseudo-ferromagnets. In addition to the interlayer...
Thermodynamic and Tunneling Density of States of the Integer Quantum Hall Critical State (2001)
Yang, S. -R. Eric, Wang, Ziqiang, MacDonald, A. H.
We examine the long wave length limit of the self-consistent Hartree-Fock approximation irreducible static density-density response function by evaluating the charge induced by an external charge....
2D bands and electron-phonon interactions in polyacene plastic transistors (2001)
Sinova, Jairo, Schliemann, John, Núñez, Alvaro S., MacDonald, A. H.
We present a simple tight-binding model for the two-dimensional energy bands of polyacene field-effect transistors and for the coupling of these bands to lattice vibrations of their host molecular...
Tomonaga-Luttinger parameters for quantum wires (2001)
Häusler, Wolfgang, Kecke, Lars, MacDonald, A. H.
The low-energy properties of a homogeneous one-dimensional electron system are completely specified by two Tomonaga-Luttinger parameters $K_{\rho}$ and $v_{\sigma}$. In this paper we discuss...
Phase transition and spin-wave dispersion in quantum Hall bilayers at filling factor nu=1 (2001)
Burkov, Anton, Schliemann, John, MacDonald, A. H., Girvin, S. M.
We present an effective Hamiltonian for a bilayer quantum Hall system at filling factor $\nu=1$ neglecting charge fluctuations. Our model is formulated in terms of spin and pseudospin operators and...
Resistance spikes and domain wall loops in Ising quantum Hall ferromagnets (2001)
Jungwirth, T., MacDonald, A. H.
We explain the recent observation of resistance spikes and hysteretic transport properties in Ising quantum Hall ferromagnets in terms of the unique physics of their domain walls. Self-consistent...
Quantum Hall Stripe States in a Tilted Magnetic Field (2001)
Jungwirth, T., MacDonald, A. H., Smrčka, L., Girvin, S. M.
A strong anisotropy in the longitudinal resistivity of a 2D electron system has been observed at half-filled high Landau levels. We report on detailed Hartree-Fock calculations of the unidirectional...
Incommensurate ground state of double-layer quantum Hall systems (2001)
Hanna, C. B., MacDonald, A. H., Girvin, S. M.
Double-layer quantum Hall systems possess interlayer phase coherence at sufficiently small layer separations, even without interlayer tunneling. When interlayer tunneling is present, application of a...
2D Bands and Electron-Phonon Interactions in Polyacene Plastic Transistors (2001)
MacDonald, A. H., Núñez, Alvaro S., Schliemann, John, Sinova, Jairo
Theory of Tunneling Spectroscopy in Ferromagnetic Nanoparticles (2000)
Canali, C. M., MacDonald, A. H.
We present a theory of the low-energy excitations of a ferromagnetic metal nanoparticle. In addition to the particle-hole excitations, which occur in a paramagnetic metal nanoparticle, we predict a...
Double-Occupancy Errors, Adiabaticity, and Entanglement of Spin-Qubits in Quantum Dots (2000)
Schliemann, John, Loss, Daniel, MacDonald, A. H.
Quantum gates that temporarily increase singlet-triplet splitting in order to swap electronic spins in coupled quantum dots, lead inevitably to a finite double-occupancy probability for both dots. By...
Strong Correlation to Weak Correlation Phase Transition in Bilayer Quantum Hall Systems (2000)
Schliemann, John, Girvin, S. M., MacDonald, A. H.
At small layer separations, the ground state of a nu=1 bilayer quantum Hall system exhibits spontaneous interlayer phase coherence and has a charged-excitation gap E_g. The evolution of this state...
Hartree-Fock Theory of Hole Stripe States (2000)
Kim, Tae-Suk, Yang, S. R. Eric, MacDonald, A. H.
We report on Hartree-Fock theory results for stripe states of two-dimensional hole systems in quantum wells grown on GaAs (311)A substrates. We find that the stripe orientation energy has a rich...
Spin and Charge Luttinger-Liquid Parameters of the One-Dimensional Electron Gas (2000)
Creffield, C. E., Häusler, Wolfgang, MacDonald, A. H.
Low-energy properties of the homogeneous electron gas in one dimension are completely described by the group velocities of its charge (plasmon) and spin collective excitations. Because of the long...
Disorder and interactions in quantum Hall ferromagnets near $\nu=1$ (2000)
Sinova, Jairo, MacDonald, A. H., Girvin, S. M.
We report on a finite-size Hartree-Fock study of the competition between disorder and interactions in a two-dimensional electron gas near Landau level filling factor $\nu=1$. The ground state at...
Reorientation of Anisotropy in a Square Well Quantum Hall Sample (2000)
Pan, W., Jungwirth, T., Stormer, H. L., Tsui, D. C., MacDonald, A. H., Girvin, S. M., ...
We have measured magnetotransport at half-filled high Landau levels in a quantum well with two occupied electric subbands. We find resistivities that are {\em isotropic} in perpendicular magnetic...
Pseudospin Anisotropy Classification of Quantum Hall Ferromagnets (2000)
Jungwirth, T., MacDonald, A. H.
Broken symmetry ground states with uniform electron density are common in quantum Hall systems when two Landau levels simultaneously approach the chemical potential at integer filling factor $\nu$....
Phonon-mediated drag at $\nu=1/2$: A test of the Chern-Simons composite fermion theory (2000)
Bonsager, Martin C., Kim, Yong Baek, MacDonald, A. H.
We report on a study of the phonon-mediated frictional drag between two-dimensional electron layers at the Landau level filling factor $\nu=1/2$ predicted by Chern-Simons composite-fermion theory....
Theory of Ferromagnetism in Diluted Magnetic Semiconductor Quantum Wells (2000)
Lee, Byounghak, Jungwirth, T., MacDonald, A. H.
We present a mean field theory of ferromagnetism in diluted magnetic semiconductor quantum wells. When subband mixing due to exchange interactions between quantum well free carriers and magnetic...
Bilayer Quantum Hall Systems at Filling Factor \nu=2: An Exact Diagonalisation Study (1999)
Schliemann, John, MacDonald, A. H.
We present an exact diagonalisation study of bilayer quantum Hall systems at a filling factor of two in the spherical geometry. We find the high-Zeeman-coupling phase boundary of the broken symmetry...
Umklapp scattering at reconstructed quantum-Hall edges (1999)
Zuelicke, U., MacDonald, A. H.
We study the low-lying excitations of a quantum-Hall sample that has undergone edge reconstruction such that there exist three branches of chiral edge excitations. Among the interaction processes...
Spin Bottlenecks in the Quantum Hall Regim (1999)
We present a theory of time-dependent tunneling between a metal and a partially spin-polarized two-dimensional electron system (2DES). We find that the leakage current which flows to screen an...
Field-tilt Anisotropy Energy in Quantum Hall Stripe States (1999)
Jungwirth, T., MacDonald, A. H., Smrcka, L., Girvin, S. M.
Recently reported giant anisotropy in the longitudinal resistivity of a 2D electron system with valence Landau level index $N \ge 2$ has been interpreted as a signal of unidirectional charge density...
Fractional-quantum-Hall edges at filling factor 1-1/m (1999)
Zuelicke, U., MacDonald, A. H., Johnson, M. D.
We consider the edge of a two-dimensional electron system that is in the quantum-Hall-effect regime at filling factor 1-1/m with m being an odd integer, where microscopic theory explaining the...
Quantum Dynamics of Pseudospin Solitons in Double-Layer Quantum Hall Systems (1999)
Kyriakidis, Jordan, Loss, Daniel, MacDonald, A. H.
Pseudospin solitons in double-layer quantum Hall systems can be introduced by a magnetic field component coplanar with the electrons and can be pinned by applying voltages to external gates. We...
Nondissipative Drag Conductance as a Topological Quantum Number (1999)
We show in this paper that the boundary condition averaged nondissipative drag conductance of two coupled mesoscopic rings with no tunneling, evaluated in a particular many-particle eigenstate, is a...
Broken Symmetry Ground States in \nu=2 Bilayer Quantum Hall Systems (1999)
MacDonald, A. H., Rajaraman, R., Jungwirth, T.
We report on a study of a bilayer two-dimensional electron gas at Landau level filling factor $\nu=2$. The system exhibits both magnetic and spontaneous interlayer phase coherence broken symmetries....
Interlayer coupling in ferromagnetic semiconductor superlattices (1998)
Jungwirth, T., Atkinson, W. A., Lee, B. H., MacDonald, A. H.
We develop a mean-field theory of carrier-induced ferromagnetism in diluted magnetic semiconductors. Our approach represents an improvement over standard RKKY model allowing spatial inhomogeneity of...
Itinerant Electron Ferromagnetism in the Quantum Hall Regime (1998)
Kasner, Marcus, Palacios, J. J., MacDonald, A. H.
We report on a study of the temperature and Zeeman-coupling-strength dependence of the one-particle Green's function of a two-dimensional (2D) electron gas at Landau level filling factor $\nu =1$...
Magnons and skyrmions in fractional Hall ferromagnets (1998)
MacDonald, A. H., Palacios, J. J.
Recent experiments have established a qualitative difference between the magnetization temperature-dependences $M(T)$ of quantum Hall ferromagnets at integer and fractional filling factors. We...
Properties of the Soliton-Lattice State in Double-Layer Quantum Hall Systems (1998)
Hanna, C. B., MacDonald, A. H., Girvin, S. M.
Application of a sufficiently strong parallel magnetic field $B_\parallel > B_{c}$ produces a soliton-lattice (SL) ground state in a double-layer quantum Hall system. We calculate the ground-state...
Magnetic Anisotropy in Quantum Hall Ferromagnets (1998)
Jungwirth, T., Shukla, S. P., Smrcka, L., Shayegan, M., MacDonald, A. H.
We show that the sign of magnetic anisotropy energy in quantum Hall ferromagnets is determined by a competition between electrostatic and exchange energies. Easy-axis ferromagnets tend to occur when...
Periphery deformations and tunneling at correlated quantum-Hall edges (1998)
Zuelicke, U., MacDonald, A. H.
We argue that, at any filling factor, correlated quantum-Hall systems possess a set of chiral boson excitations which are generated by electronically rigid deformations of the system's periphery. We...
Observability of counterpropagating modes at fractional-quantum-Hall edges (1998)
Zuelicke, U., MacDonald, A. H., Johnson, M. D.
When the bulk filling factor is equal to 1 - 1/m with m odd, at least one counterpropagating chiral collective mode occurs simultaneously with magnetoplasmons at the edge of fractional-quantum-Hall...
Engineering Superfluidity in Electron-Hole Double Layers (1998)
Sergio Conti, Sergio Conti, Giovanni Vignale, Giovanni Vignale, A. H. Macdonald, A. H. Macdonald
We show that band-structure effects are likely to prevent superfluidity in semiconductor electron-hole double-layer systems. We suggest the possibility that superfluidity could be realized by the...
Bulk charge distributions on integer and fractional quantum Hall plateaus (1997)
Palacios, J. J., MacDonald, A. H.
We discuss the charge distributions across the bulk of a two-dimensional electron gas system which is on an integer or fractional quantum Hall plateau. Our analysis is based on a relation, derived...
Mode Mixing in Antiferromagnetically Correlated Double Quantum Wells (1997)
Radtke, R. J., Sarma, S. Das, MacDonald, A. H.
We examine the robustness of a recently predicted exchange-induced zero-field magnetic phase in semiconductor double quantum wells in which each well is spin-polarized and the polarization vectors...
Abolfath, M., Palacios, J. J., Fertig, H. A., Girvin, S. M., MacDonald, A. H.
We report on a study of the classical field theory description of charged skyrmions in quantum Hall ferromagnets. The appropriate field theory is a non-linear $\sigma$ model generalized to include...
Collective Excitations, NMR, and Phase Transitions in Skyrme Crystals (1997)
Cote, R., MacDonald, A. H., Brey, Luis, Fertig, H. A., Girvin, S. M., Stoof, H. T. C.
At Landau level filling factors near nu =1, quantum Hall ferromagnets form a Skyrme crystal state with quasi-long-range translational and non-collinear magnetic order. We develop an effective low...
Virial Expansions, Exclusion Statistics, and the Fractional Quantum Hall Effect (1997)
Tevosyan, Kahren, MacDonald, A. H.
We report on a study of virial expansions for interacting electrons in the lowest Landau level of a two-dimensional electron gas. For hard-core-model interactions, we derive analytic results valid at...
Collective excitations, NMR, and phase transitions in Skyrme Crystals (1997)
Côté, R., MacDonald, A.H., Brey, L., Fertig, H.A., Girvin, S.M., Stoof, H.T.C.
At Landau level filling factors near ν = 1, quantum Hall ferromagnets form a Skyrme crystal state with quasi-long-range translational and noncollinear magnetic order. We develop an effective low...
Hartree-Fock Theory of Skyrmions in Quantum Hall Ferromagnets (1996)
Fertig, H. A., Brey, L., Cote, R., MacDonald, A. H., Karlhede, A., Sondhi, S. L.
We report on a study of the charged-skyrmion or spin-texture excitations which occur in quantum Hall ferromagnets near odd Landau level filling factors. Particle-hole symmetry is used to relate the...
Swierkowski, L., MacDonald, A. H.
The subbands of weakly coupled double-layer two dimensional electron gas systems consist of narrowly spaced pairs whose corresponding wavefunctions are symmetric and antisymmetric combinations of...
Edge-Magnetoplasmon Wave-Packet Revivals in the Quantum Hall Effect (1996)
Zuelicke, U., Bluhm, R., Kostelecky, V. A., MacDonald, A. H.
The quantum Hall effect is necessarily accompanied by low-energy excitations localized at the edge of a two-dimensional electron system. For the case of electrons interacting via the long-range...
Evidence for virtual-phonon exchange in semiconductor heterostructures (1993)
Gramila, T. J., Eisenstein, J. P., MacDonald, A. H., Pfeiffer, L. N., West, K. W.
Measurements of frictional drag between adjacent electron gases in double quantum wells provide strong evidence for phonon-mediated electron-electron interactions. These interactions, which dominate...
Mutual friction between parallel two-dimensional electron systems (1991)
Gramila, T. J., Eisenstein, J. P., MacDonald, A. H., Pfeiffer, L. N., West, K. W.
Frictional drag between isolated two-dimensional electron gases separated by a thin barrier has been observed at low temperatures in GaAs/AlGaAs double-quantum-well structures. Separate electrical...