Unconventional superconductivity on a topological insulator (2009)
Linder, Jacob, Tanaka, Yukio, Yokoyama, Takehito, Sudbø, Asle, Nagaosa, Naoto
We study proximity-induced superconductivity on the surface of a topological insulator (TI), focusing on unconventional pairing. We find that the excitation spectrum becomes gapless for any...
Anomalous magnetoresistance on the topological surface (2009)
Yokoyama, Takehito, Tanaka, Yukio, Nagaosa, Naoto
We investigate charge transport in two-dimensional ferromagnet/feromagnet junction on a topological insulator. The conductance across the interface depends sensitively on the directions of the...
Tanaka, Yukio, Yokoyama, Takehito, Nagaosa, Naoto
We study theoretically charge transport properties of normal metal (N) / ferromagnet insulator (FI) / superconductor (S) junction and S/FI/S junction formed on the surface of three-dimensional...
Electro-spinon in one-dimensional Mott insulator (2009)
Katsura, Hosho, Sato, Masahiro, Furuta, Takashi, Nagaosa, Naoto
The low-energy dynamical optical response of dimerized and undimerized spin liquid states in a one-dimensional charge transfer Mott insulator is theoretically studied. An exact analysis is given for...
De Filippis, Giulio Dr., Cataudella, Vittorio, Mishchenko, Andrey Dr., Perroni, Carmine Dr. Antonio, Nagaosa, Naoto
The optical conductivity (OC) of cuprates is studied theoretically in the low density limit of the t-t'-J-Holstein model. By developing a limited phonon basis exact diagonalization (LPBED) method...
Holstein polaron in the presence of disorder (2009)
Berciu, Mona, Mishchenko, Andrei S., Nagaosa, Naoto
Non-local, inhomogeneous and retarded response observed in experiments is reproduced by introducing the Inhomogeneous Momentum Average (IMA) method to study single polaron problems with disorder in...
Purely electric spin pumping in one-dimension (2009)
Avishai, Yshai, Cohen, Doron, Nagaosa, Naoto
We show theoretically that a simple one dimensional system (such as metallic wire) can display quantum spin pumping possibly without pushing any charge. It is achieved by applying two slowly varying...
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...
Theory of Thermal Hall Effect in Quantum Magnets (2009)
Katsura, Hosho, Nagaosa, Naoto, Lee, Patrick A
We present a theory of thermal Hall effect in insulating quantum magnets, where the heat current is totally carried by charge-neutral objects such as magnons and spinons. Two distinct types of...
Interacting two helical edge modes in quantum spin Hall systems (2009)
We study theoretically the two interacting one-dimensional helical modes at the edges of the quantum spin Hall systems. A new type of inter-edge correlated liquid (IECL) without the spin gap is...
Skyrmions and Anomalous Hall Effect in a Dzyloshinskii-Moriya Spiral Magnet (2009)
Yi, Su Do, Onoda, Shigeki, Nagaosa, Naoto, Han, Jung Hoon
Monte Carlo simulation study of a classical spin model with Dzylosinskii-Moriya interaction and the spin anisotropy under the magnetic field is presented. We found a rich phase diagram containing the...
Giant spin rotation in the normal metal/quantum spin Hall junction (2009)
Yokoyama, Takehito, Tanaka, Yukio, Nagaosa, Naoto
We study theoretically reflection problem in the junction between a normal metal and an insulator characterized by a parameter $M$, which is a usual insulator for $M>0$ or a quantum spin Hall system...
De Filippis, Giulio, Cataudella, Vittorio, Mishchenko, Andrey, Antonio Perroni, Carmine, Nagaosa, Naoto
The optical conductivity (OC) of cuprates is studied theoretically in the low density limit of the t-t'-J-Holstein model. By developing a limited phonon basis exact diagonalization (LPBED) method...
De Filippis, Giulio, Cataudella, Vittorio, Mishchenko, Andrey, Antonio Perroni, Carmine, Nagaosa, Naoto
The optical conductivity (OC) of cuprates is studied theoretically in the low density limit of the t-t'-J-Holstein model. By developing a limited phonon basis exact diagonalization (LPBED) method...
Spin Hall Effect of Excitons (2008)
Kuga, Shun-ichi, Murakami, Shuichi, Nagaosa, Naoto
Spin Hall effect for excitons in alkali halides and in Cu_2O is investigated theoretically. In both systems, the spin Hall effect results from the Berry curvature in k space, which becomes nonzero...
Enhanced spin Hall effect by resonant skew scattering in orbital-selective Kondo effect (2008)
Guo, Guang-Yu, Maekawa, Sadamichi, Nagaosa, Naoto
The enhanced spin Hall effect in Au metal due to the resonant skew scattering is studied with first-principles band structure calculations. Especially the gigantic spin Hall angle $\gamma_S \cong...
Topological states in a transition metal oxide Na2IrO3 (2008)
Shitade, Atsuo, Katsura, Hosho, Qi, Xiao-Liang, Zhang, Shou-Cheng, Nagaosa, Naoto
The electronic state of an Ir oxide, Na$_2$IrO$_3$ with the honeycomb structure is analyzed theoretically as a representative system where both the spin-orbit interaction and the electron correlation...
Current-induced dynamics of spiral magnet (2008)
Goto, Kohei, Katsura, Hosho, Nagaosa, Naoto
We study the dynamics of the spiral magnet under the charge current by solving the Landau-Lifshitz-Gilbert equation numerically. In the steady state, the current ${\vec j}$ induces (i) the parallel...
Topological spin-current in non-centrosymmetric superconductors (2008)
Tanaka, Yukio, Yokoyama, Takehito, Balatsky, Alexander V., Nagaosa, Naoto
We study the spin transport properties of the non-centrosymmetric superconductor with time-reversal-symmetry where spin-triplet $(p_{x} \pm i p_{y})$-wave and spin-singlet s-wave pair potential can...
Nematic and chiral orders for planar spins on triangular lattice (2008)
Park, Jin-Hong, Onoda, Shigeki, Nagaosa, Naoto, Han, Jung Hoon
We propose a variant of the antiferromagnetic XY model on the triangular lattice to study the interplay between the chiral and nematic orders in addition to the magnetic order. The model has a...
Quantum Dynamics of Multiferroic Helimagnets: a Schwinger-Boson Approach (2008)
Katsura, Hosho, Onoda, Shigeki, Han, Jung Hoon, Nagaosa, Naoto
We study the quantum dynamics/fluctuation of the cycloidal helical magnet in terms of the Schwinger boson approach. In sharp contrast to the classical fluctuation, the quantum fluctuation is...
Field-induced metal-insulator transition and switching phenomenon in correlated insulators (2007)
Sugimoto, Naoyuki, Onoda, Shigeki, Nagaosa, Naoto
We study the nonequilibrium switching phenomenon associated with the metal-insulator transition under electric field E in correlated insulator by a gauge-covariant Keldysh formalism. Due to the...
Onoda, Shigeki, Sugimoto, Naoyuki, Nagaosa, Naoto
The mechanism of the anomalous Hall transport phenomena, if it is of the intrinsic or extrinsic origin, has been controversial. We present a unified theory of them for ferromagnetic metals with...
Electron Correlation and Jahn-Teller Interaction in Manganese Oxides (2007)
Naoto Nagaosa, Shuichi Murakami, Hyun Cheol Lee
The interplay between the electron repulsion U and the Jahn-Teller electronphonon interation ELR is studied with a large d model for the ferromagnetic state of the manganese oxides. These two...
Tuning phase transition between quantum spin Hall and ordinary insulating phases (2007)
Murakami, Shuichi, Iso, Satoshi, Avishai, Yshai, Onoda, Masaru, Nagaosa, Naoto
An effective theory is constructed for analyzing a generic phase transition between the quantum spin Hall and the insulator phases. Occurrence of degeneracies due to closing of the gap at the...
Chiral spin pairing in helical magnets (2007)
Onoda, Shigeki, Nagaosa, Naoto
The Ginzburg-Landau Hamiltonian for incommensurate frustrated classical spin systems is analyzed. The coupling to phonons through the Dzyaloshinskii-Moriya interaction and/or the four-spin exchange...
Left-handed Ferromagnet (2007)
Onoda, Masaru, Mishchenko, Andrei S., Nagaosa, Naoto
The dynamics of the total magnetization in metallic ferromagnet is studied theoretically taking into account the relativistic spin-orbit interaction. It is found that its quantum dynamics is...
Quantum charge pumping and electric polarization in Anderson insulators (2007)
Chern, Chyh-Hong, Onoda, Shigeki, Murakami, Shuichi, Nagaosa, Naoto
We investigate adiabatic charge pumping in disordered system in one dimension with open and closed boundary conditions. In contrast to the Thouless charge pumping, the system has no gap even though...
Spin-polarization coupling in multiferroic transition-metal oxides (2007)
Jia, Chenglong, Onoda, Shigeki, Nagaosa, Naoto, Han, Jung Hoon
A systematic microscopic theory of magnetically induced ferroelectricity and lattice modulation is presented for all electron configurations of Mott-insulating transition-metal oxides. Various...
Bond electronic polarization induced by spin (2006)
Jia, Chenglong, Onoda, Shigeki, Nagaosa, Naoto, Han, Jung Hoon
We study theoretically the electric polarization induced by noncollinear spin configurations in the limit of strong Hund coupling. We employ a model of two magnetic ions sandwitching an oxygen ion....
Geometrical Aspects in Optical Wavepacket Dynamics (2006)
Onoda, Masaru, Murakami, Shuichi, Nagaosa, Naoto
We construct a semiclassical theory for propagation of an optical wavepacket in non-conducting media with periodic structures of dielectric permittivity and magnetic permeability, i.e.,...
Intrinsic vs. extrinsic anomalous Hall effect in ferromagnets (2006)
Onoda, Shigeki, Sugimoto, Naoyuki, Nagaosa, Naoto
A unified theory of the anomalous Hall effect (AHE) is presented for multi-band ferromagnetic metallic systems with dilute impurities. In the clean limit, the AHE is mostly due to the extrinsic...
Localization in a quantum spin Hall system (2006)
Onoda, Masaru, Avishai, Yshai, Nagaosa, Naoto
Localization problem of electronic states in a two-dimensional quantum spin Hall system (QSH - a symplectic model with a non-trivial topological structure) is studied by the transfer matrix method....
Onoda, Shigeki, Sugimoto, Naoyuki, Nagaosa, Naoto
We develop a general theory of non-equilibrium states based on the Keldysh formalism, in particular, for charged-particle systems under static uniform electromagnetic fields. The Dyson equation for...
Enhanced dielectric response by disordered nanoscale/mesoscopic insulators (2006)
Onoda, Shigeki, Chern, Chyh-Hong, Murakami, Shuichi, Ogimoto, Yasushi, Nagaosa, Naoto
Enhancement of the dielectric response of insulators by disorder is theoretically proposed, where the quantum interference of electronic waves through the nanoscale/mesoscopic system and its change...
Disorder effect on the localization/delocalization in incommensurate potential (2006)
The interplay between incommensurate (IC) and random potentials is studied in a two-dimensional symplectic model with the focus on localization/delocalization problem. With the IC potential only,...
Electron localization/delocalization in incommensurate helical magnets (2006)
Tanaka, Shu, Katsura, Hosho, Nagaosa, Naoto
The electronic states in incommensurate (IC) helical magnets are studied theoretically from the viewpoint of the localization/delocalization. It is found that in the multi-band system with...
Dynamical magneto-electric coupling in helical magnets (2006)
Katsura, Hosho, Balatsky, Alexander V., Nagaosa, Naoto
Collective mode dynamics of the helical magnets coupled to electric polarization via spin-orbit interaction is studied theoretically. The soft modes associated with the ferroelectricity are not the...
Dynamical Diffraction Theory for Wave Packet Propagation in Deformed Crystals (2006)
Sawada, Kei, Murakami, Shuichi, Nagaosa, Naoto
We develop a theory for the trajectory of an x ray in the presence of a crystal deformation. A set of equations of motion for an x-ray wave packet including the dynamical diffraction is derived,...
Katsura, Hosho, Balatsky, Alexander V., Nussinov, Zohar, Nagaosa, Naoto
We present a theory of Landau-Lifshitz-Gilbert damping $\alpha$ for a localized spin ${\vec S}$ in the junction coupled to the conduction electrons in both leads under an applied volatege $V$. We...
The generalized equation of motion for the orbital dynamics in the presence of current (2005)
Chern, Chyh-Hong, Nagaosa, Naoto
The orbital dynamics induced by the charge current is studied theoretically. The equation of motion for the isospin vector $T^A$ in the SU(N) case is derived in the presence of the current, and is...
Interfaces of correlated electron systems: Proposed mechanism for colossal electroresistance (2005)
Mott's metal-insulator transition at an interface due to band bending is studied by the density matrix renormalization group (DMRG). We show that the result can be recovered by a simple modification...
Dynamics of localized spins coupled to the conduction electrons with charge/spin currents (2005)
The effects of the charge/spin currents of conduction electrons on the dynamics of the localized spins are studied in terms of the perturbation in the exchange coupling $J_{K}$ between them. The...
We theoretically propose that the optical analog of a Lorentz force acting on a ray of light is realized in multiferroic materials such as GaFeO$_3$ showing the magnetoelectric effect. The toroidal...
Bensimon, Damien, Nagaosa, Naoto
The extended $t-J$ model is theoretically studied, in the context of hole underdoped cuprates. Based on results obtained by recent numerical studies, we identify the mean field state having both the...
Spin current and accumulation generated by spin Hall insulator (2005)
Spin current and accumulation generated by the electric field in spin Hall insulator (SHI) are investigated theoretically in terms of the Keldysh formalism. In contrast to the quantum Hall system,...
Role of relaxation in spin Hall effect (2005)
The role of the relaxation due to the impurity scattering and/or the contacts to leads/electrodes are studied for the spin Hall effect (SHE). Relaxation is essential to attain the steady state and...
Spin Hall effect of conserved current: Conditions for a nonzero spin Hall current (2005)
Sugimoto, Naoyuki, Onoda, Shigeki, Murakami, Shuichi, Nagaosa, Naoto
We study the spin Hall effect taking into account the impurity scattering effect as general as possible with the focus on the definition of the spin current. The conserved bulk spin current (Shi et...
Gigantic Enhancement of Magneto-Chiral Effect in Photonic Crystals (2005)
We theoretically propose a method to enhance dramatically a magneto-chiral(MC) effect by using the photonic crystals composed of a multiferroic material. The MC effect, the directional birefringence...
Spin current and magneto-electric effect in non-collinear magnets (2004)
Katsura, Hosho, Nagaosa, Naoto, Balatsky, Alexander V.
A new microscopic mechanism of the magneto-electric (ME) effect based on the spin supercurrent is theoretically presented for non-collinear magnets. The close analogy between the superconductors...
Doping a Mott Insulator: Physics of High Temperature Superconductivity (2004)
Lee, Patrick A., Nagaosa, Naoto, Wen, Xiao-Gang
This article reviews the effort to understand the physics of high temperature superconductors from the point of view of doping a Mott insulator. The basic electronic structure of the cuprates is...
Quantum Versus Jahn-Teller Orbital Physics in YVO$_3$ and LaVO$_3$ (2004)
We argue that the large Jahn-Teller (JT) distortions in YVO$_3$ and LaVO$_3$ should suppress the quantum orbital fluctuation. The unusual magnetic properties can be well explained based on LDA+$U$...
Entropy-Driven Reentrant Behavior in CMR Manganites (2004)
Furukawa, Nobuo, Motome, Yukitoshi, Nagaosa, Naoto
We discuss the origin of the reentrant behaviors of insulating states above the Curie temperature of the colossal magnetoresistance manganites. We consider a system where charge ordering and...
Motome, Yukitoshi, Furukawa, Nobuo, Nagaosa, Naoto
We theoretically explore the mechanism of the colossal magnetoresistance in manganese oxides by explicitly taking into account the phase competition between the double-exchange ferromagnetism and the...
Re-entrant Behavior and Gigantic Response in Disordered Spin-Peierls System (2004)
Seo, Hitoshi, Motome, Yukitoshi, Nagaosa, Naoto
Effects of disorder and external field on the competing spin-Peierls and antiferromagnetic states are studied theoretically in terms of the numerical transfer matrix method applied to a quasi...
Murakami, Shuichi, Nagaosa, Naoto, Zhang, Shou-Cheng
Recent theories predict dissipationless spin current induced by an electric field in doped semiconductors. Nevertheless, the charge current is still dissipative in these systems. In this work, we...
Anomalous Hall Effect and Skyrmion Number in Real- and Momentum-space (2004)
Onoda, Masaru, Tatara, Gen, Nagaosa, Naoto
We study the anomalous Hall effect (AHE) for the double exchange model with the exchange coupling $|J_H|$ being smaller than the bandwidth $|t|$ for the purpose of clarifying the following unresolved...
Onoda, Masaru, Murakami, Shuichi, Nagaosa, Naoto
We derive the semiclassical equation of motion for the wave-packet of light taking into account the Berry curvature in the momentum space. This equation naturally describes the interplay between the...
On the stability of U(1) spin liquids in two dimensions (2004)
Hermele, Michael, Senthil, T., Fisher, Matthew P. A., Lee, Patrick A., Nagaosa, Naoto, Wen, Xiao-Gang
We establish that spin liquids described in terms of gapless fermionic (Dirac) spinons and gapless U(1) gauge fluctuations can be stable in two dimensions, at least when the physical SU(2) spin...
Topological nature of polarization and charge pumping in ferroelectrics (2004)
Onoda, Shigeki, Murakami, Shuichi, Nagaosa, Naoto
Electric polarization or transferred charge due to an adiabatic change of external parameters $\vec{Q}$ is expressed in terms of a vector field defined in the $\vec{Q}$ space. This vector field is...
Orbital Dependent Phase Control in Ca2-xSrxRuO4 (2004)
Fang, Zhong, Nagaosa, Naoto, Terakura, Kiyoyuki
We present first-principles studies on the orbital states of the layered perovskites Ca$_{2-x}$Sr$_x$RuO$_4$. The crossover from antiferromagnetic (AF) Mott insulator for $x < 0.2$ to nearly...
Ishihara, Sumio, Nagaosa, Naoto
We study the electron-phonon interaction in the strongly correlated superconducting cuprates. Two types of the electron-phonon interactions are introduced in the $t-J$ model; the diagonal and...
SU(2) Non-Abelian Holonomy and Dissipationless Spin Current in Semiconductors (2003)
Murakami, Shuichi, Nagaosa, Naoto, Zhang, Shou-Cheng
Following our previous work [S. Murakami, N. Nagaosa, S. C. Zhang, Science 301, 1348 (2003)] on the dissipationless quantum spin current, we present an exact quantum mechanical calculation of this...
Dissipationless Quantum Spin Current at Room Temperature (2003)
Murakami, Shuichi, Nagaosa, Naoto, Zhang, Shou-Cheng
While microscopic laws of physics are invariant under the reversal of the arrow of time, the transport of energy and information in most devices is an irreversible process. It is this irreversibility...
Onoda, Shigeki, Nagaosa, Naoto
Interplay between the Mott transition and the multicritical phenomenon of d-wave superconductivity (SC) and antiferromagnetism (AF) is studied theoretically. We describe the Mott transition, which is...
Randomness Effect on Multicritical Phenomena in Double-Exchange Systems (2003)
Motome, Yukitoshi, Furukawa, Nobuo, Nagaosa, Naoto
Double-exchange model interacting with adiabatic phonons is studied in the presence of randomness by using the Monte-Carlo method and the systematic size-scaling analysis. A bicritical behavior is...
Competing Orders and Disorder-induced Insulator to Metal Transition in Manganites (2003)
Motome, Yukitoshi, Furukawa, Nobuo, Nagaosa, Naoto
Effects of disorder on the two competing phases, i.e., the ferromagnetic metal and the commensurate charge/lattice ordered insulator, are studied by Monte Carlo simulation. The disorder suppresses...
We study the effect of disorder on the anomalous Hall effect (AHE) in two-dimensional ferromagnets. The topological nature of AHE leads to the integer quantum Hall effect from a metal, i.e., the...
Geometrical aspects of Gigantic Magneto-Electric effect and Quantum Pump (2003)
Shindou, Ryuichi, Nagaosa, Naoto
We study the Magneto-Electric (ME) effect from the viewpoint of the Berry phase connection and quantum adiabatic charge transport (QAPT). The linear response theory for the electronic polarization...
Fang, Zhong, Nagaosa, Naoto, Terakura, Kiyoyuki
The anisotropy of low energy (0$\sim$5eV) optical excitations in strongly correlated transition-metal oxides is closely related to the spin and orbital orderings. The recent successes of LDA+$U$...
Lee, Patrick A., Nagaosa, Naoto
In the slave boson mean field treatment of the t-J model, the ground state for small doping is a d-wave superconductor. A conventional superconductor has collective modes associated with the...
Two-dimensional charge order in layered 2-1-4 perovskite oxides (2002)
Onoda, Shigeki, Motome, Yukitoshi, Nagaosa, Naoto
Monte Carlo simulations are performed on the three-dimensional (3D) Ising model with the 2-1-4 layered perovskite structure as a minimal model for checkerboard charge ordering phenomena in layered...
Spin Chirality Fluctuation and Anomalous Hall Effect in Itinerant Ferromagnets (2002)
Onoda, Shigeki, Nagaosa, Naoto
The anomalous Hall effect due to the spin chirality order and fluctuation is studied theoretically in a Kondo lattice model without the relativistic spin-orbit interaction. Even without the...
Theory for Slightly Doped Antiferromagnetic Mott Insulators (2002)
Lee, T. K., Ho, Chang-Ming, Nagaosa, Naoto, Lee, Wei-Cheng
Trial wavefunctions, constructed explicitly from the unique 2-dimensional Mott insulating state with antiferromagnetic order, are proposed to describe the low-energy states of a Mott insulator...
One-Dimensional Confinement and Enhanced Jahn-Teller Instability in LaVO$_3$ (2002)
Motome, Yukitoshi, Seo, Hitoshi, Fang, Zhong, Nagaosa, Naoto
Ordering and quantum fluctuations of orbital degrees of freedom are studied theoretically for LaVO$_3$ in spin-C-type antiferromagnetic state. The effective Hamiltonian for the orbital pseudospin...
Colossal magnetoresistance in manganites as a multicritical phenomenon (2002)
Murakami, Shuichi, Nagaosa, Naoto
The colossal magnetoresistance in manganites AMnO_3 is studied from the viewpoint of multicritical phenomena. To understand the complicated interplay of various phases, we study the Ginzburg-Landau...
Berry phase in Magnetic Superconductors (2002)
Murakami, Shuichi, Nagaosa, Naoto
In magnetic systems, electronic bands often acquire nontrivial topological structure characterized by gauge flux distribution in momentum (k)-space. It sometimes follows that the phase of the...
Theory of Excitonic States in CaB6 (2002)
Murakami, Shuichi, Shindou, Ryuichi, Nagaosa, Naoto, Mishchenko, Andrei S.
We study the excitonic states in CaB6 in terms of the Ginzburg-Landau theory. By minimizing the free energy and by comparing with experimental results, we identify two possible ground states with...
Particle-hole symmetry and transport properties of the flux state in underdoped cuprates (2002)
Transport properties are studied for the flux state with the gauge flux $\phi$ per plaquett, which may model the underdoped cuprates, with the emphasis on the particle-hole and parity/chiral...
Jahn-Teller effect and Electron correlation in manganites (2002)
Jahn-Teller (JT) effect both in the absence and presence of the strong Coulomb correlation is studied theoretically focusing on the reduction $\Delta K$ of the kinetic energy gain which is directly...
Topological Nature of Anomalous Hall Effect in Ferromagnet (2001)
The anomalous Hall effect in two-dimensional ferromagnets is discussed to be the physical realization of the parity anomaly in (2+1)D, and the band crossing points behave as the topological...
Orbital ferromagnetism and anomalous Hall effect in antiferromagnets on distorted fcc lattice (2001)
Shindou, Ryuichi, Nagaosa, Naoto
The Berry phase due to the spin wavefunction gives rise to the orbital ferromagnetism and anomalous Hall effect in the non-coplanar antiferromagnetic ordered state on face centered cubic (fcc)...
Theory of Ferromagnetism in Ca1-xLaxB6 (2001)
Murakami, Shuichi, Shindou, Ryuichi, Nagaosa, Naoto, Mishchenko, Andrei S.
Novel ferromagnetism in Ca$_{1-x}$La$_{x}$B$_6$ is studied in terms of the Ginzburg-Landau theory for excitonic order parameters, taking into account symmetry of the wavefunctions. We found that the...
Complex orbital state in manganites (2000)
The $e_g$-orbital states with complex coefficients of the linear combination of $x^2-y^2$ and $3z^2-r^2$ are studied for the ferromagnetic state in doped manganites. Especially the focus is put on...
Impurity Effects on Quantum Depinning of Commensurate Charge Density Waves (2000)
Yumoto, Masanori, Fukuyama, Hidetoshi, Matsukawa, Hiroshi, Nagaosa, Naoto
We investigate quantum depinning of the one-dimensional (1D) commensurate charge-density wave (CDW) in the presence of one impurity theoretically. Quantum tunneling rate below but close to the...
Ohgushi, Kenya, Murakami, Shuichi, Nagaosa, Naoto
A ferromagnet with spin anisotropies on the 2D Kagome lattice is theoretically studied. This is a typical example of the flat-band ferromagnet. The Berry phase induced by the tilting of the spins...
Murakami, Shuichi, Nagaosa, Naoto
We study theoretically the multicritical phenomena of the superconductivity (SC) and antiferromagnetism (AF) in organic conductors $\kappa$-BEDT salts. The phase diagram and the experimental data on...
Impurity pinning in transport through 1D Mott-Hubbard and spin gap insulators (1999)
Ponomarenko, Vadim, Nagaosa, Naoto
A low energy crossover (see cond-mat/9711167) induced by Fermi liquid reservoirs in transport through a 1D Mott-Hubbard insulator of finite length $L$ is examined in the presence of impurity pinning....
Orbital Polarization and Fluctuation in Manganese Oxides (1999)
In a form which include the mother compound, we studied the extended Hubbard-type model with the orbital degeneracy for any doping concentration. Meanfield phase diagram and the spin wave excitation...
Confinement and Bose Condensation in Gauge Theory of High-Tc Superconductors (1999)
Nagaosa, Naoto, Lee, Patrick A.
The issue of confinement and bose condensation is studied for gauge models of high-Tc superconductors. First the Abelian-Higgs model in (2+1)D, i.e., XY-model coupled to lattice gauge field $a_{\mu}$...
Spin and orbital ordering in double-layered manganites (1999)
We study theoretically the phase diagram of the double-layered perovskite manganites taking into account the orbital degeneracy, the strong Coulombic repulsion, and the coupling with the lattice...
Theory of spin wave excitation in manganites (1999)
The role of the orbital degrees of freedom is studied theoretically for the spin dynamics of $R_{1-x}A_x$MnO$_3$. Based on the meanfield solution, an RPA calculation has been done and it is found...
An SO(5) model of p-wave superconductivity and ferromagnetism (1998)
Murakami, Shuichi, Nagaosa, Naoto, Sigrist, Manfred
We study an SO(5) model unifying p-wave superconductivity and ferromagnetism. If only a single p-wave pairing wavefunction is involved, the p-wave superconducting (pSC) and ferromagnetic (F) states...
Fractional charge in transport through a 1D correlated insulator of finite length (1998)
Ponomarenko, Vadim, Nagaosa, Naoto
Transport through a one channel wire of length $L$ confined between two leads is examined when the 1D electron system has an energy gap $2M$: $M > T_L \equiv v_c/L$ induced by the interaction in...
Phase Diagram in Manganese Oxides (1998)
Maezono, Ryo, Ishihara, Sumio, Nagaosa, Naoto
We study theoretically the phase diagram of perovskite manganites taking into account the double degeneracy of the $e_g$ orbitals in a $Mn^{3+}$ ion. A rich phase diagram is obtained in the mean...
Lattice Instability in the Spin-Ladder System under Magnetic Field (1998)
Nagaosa, Naoto, Murakami, Shuichi
We study theoretically the lattice instability in the spin gap systems under magnetic field. With the magnetic field larger than a critical value h_{c1}, the spin gap is collapsed and the...
Lattice Instability in the Spin-Ladder System under Magnetic Field (1998)
Naoto Nagaosa, Shuichi Murakami
We study theoretically the lattice instability in the spin gap systems under magnetic field. With the magnetic field larger than a critical value h c1 , the spin gap is collapsed and the...
Transport through a 1D Mott-Hubbard insulator of finite length (1997)
Ponomarenko, Vadim, Nagaosa, Naoto
Transport through a 1D Mott-Hubbard insulator of a finite length $L$ is studied beyond perturbative approach. At special value of the low energy constant of the interaction we have mapped the problem...
Quantum transport in $\nu=2/3$ spin-singlet quantum Hall edges (1997)
Imura, Ken-ichiro, Nagaosa, Naoto
Tunneling conductance $G(T)$ through a constricted point contact is studied for the $\nu=2/3$ spin-singlet edges. Including spin-flip tunneling, Zeeman splitting and random magnetic impurities, we...
Electron Correlation and Jahn-Teller Interaction in Manganese Oxides (1997)
Nagaosa, Naoto, Murakami, Shuichi, Lee, Hyun Cheol
The interplay between the electron repulsion $U$ and the Jahn-Teller electron-phonon interation $E_{LR}$ is studied with a large $d$ model for the ferromagnetic state of the manganese oxides. These...
Features of renormalization induced by interaction in 1D transport (1997)
Ponomarenko, Vadim, Nagaosa, Naoto
One-dimensional interacting electrons in a quantum wire connected to reservoirs are studied theoretically. The difference in the Tomonaga-Luttinger interaction constants between the wire (g) and...
From Tomonaga-Luttinger to Fermi liquid in transport through a tunneling barrier (1997)
Ponomarenko, Vadim, Nagaosa, Naoto
Finite length of a one channel wire results in crossover from a Tomonaga-Luttinger to Fermi liquid behavior with lowering energy scale. In condition that voltage drop $(V)$ mostly occurs across a...
Imura, Ken-ichiro, Nagaosa, Naoto
We study the effects of long-range Coulomb interaction (LRCI) on the quantum transport in FQH edges with $\nu=1/(2k+1)$. We consider two models, i.e., the quasi-particle tunneling (QPT) model and the...
Phase Diagram in R_{1-x}A_xMnO_3 (1997)
Maezono, Ryo, Ishihara, Sumio, Nagaosa, Naoto
We study the phase diagram of R_{1-x}A_xMnO_3 (R=La, Pr, Nd, Sm ; A=Ca, Sr, Ba) by taking into account the degeneracy of $e_g$ orbitals and the anisotropy of the transfer integral. The...
Spin-Charge Separation in Angle-Resolved Photoemission Spectra (1997)
Suzuura, Hidekatsu, Nagaosa, Naoto
The implications of the angle-resolved photoemission spectroscopy (ARPES) on the issue of spin-charge separation are discussed from the viewpoint of slave-particle RVB theories. It is pointed out...
Kondo Effect in High-T_c Cuprates (1997)
Nagaosa, Naoto, Lee, Patrick A.
We study the Kondo effect due to the nonmagnetic impurity, e.g., Zn, in high-T_c cuprates based on the spin-change separated state. In the optimal or overdoped case with the Kondo screening, the...
Threshold features in transport through a 1D constriction (1997)
Ponomarenko, Vadim, Nagaosa, Naoto
Suppression of electron current $ \Delta I$ through a 1D channel of length $L$ connecting two Fermi liquid reservoirs is studied taking into account the Umklapp electron-electron interaction induced...
An SU(2) Formulation of the t-J model: Application to Underdoped Cuprates (1997)
Lee, Patrick A., Nagaosa, Naoto, Ng, Tai-Kai, Wen, Xiao-Gang
We develop a slave-boson theory for the t-J model at finite doping which respect a SU(2) symmetry -- a symmetry previously known to be important at half filling. The mean field phase diagram is found...
Orbital Liquid in Perovskite Transition-Metal Oxides (1996)
Ishihara, Sumio, Yamanaka, Masanori, Nagaosa, Naoto
We study the effects of the degeneracy of the $e_g$ orbitals as well as the double exchange interaction with $t_{2g}$ spins in perovskite transition-metal oxides. In addition to the spin field ${\vec...
Edge Modes in the Hierarchical Fractional Quantum Hall Liquids with Coulomb Interaction (1996)
Morinari, Takao, Nagaosa, Naoto
Edge modes are studied for the hierarchical fractional quantum Hall liquids (FQHL) by treating the edge and bulk in a unified fashion. Within the RPA treatment of the composite boson effective theory...
Conductance through a Magnetic Domain Wall in Double Exchange System (1996)
Yamanaka, Masanori, Nagaosa, Naoto
The conductance through a magnetic domain wall is calculated for the double exchange system as a function of energy and the width of the domain wall. It is shown that when the carrier density is low...
Tunneling through a barrier in Tomonaga-Luttinger liquid connected to reservoirs (1996)
Furusaki, Akira, Nagaosa, Naoto
The transport through a barrier is studied for a Tomonaga-Luttinger liquid of finite length connected to reservoirs. An effective action for the phase variable at the barrier is derived for spatially...
Nonmagnetic impurity in spin gap state (1995)
The effects of the nonmagnetic strong scatterers (unitary limit) on the magnetic and transport properties are studied for RVB states in both slave-boson and slave-fermion mean field theories with the...
Edge and Bulk of the Fractional Quantum Hall Liquids (1995)
Nagaosa, Naoto, Kohmoto, Mahito
An effective Chern-Simons theory for the Abelian quantum Hall states with edges is proposed to study the edge and bulk properties in a unified fashion. We impose a condition that the currents do not...
Chiral Anomaly and Spin Gap in One-Dimensional Interacting Fermions (1994)
Nagaosa, Naoto, Oshikawa, Masaki
Semiclassical approach has been developed for the one-dimensional interacting fermion systems. Starting from the incommensurate spin density wave (SDW) mean field state for the repulsive Hubbard...