A. H. Castro Neto

Vortex liquid crystals in anisotropic type II superconductors (2002)

Recent experimental evidence shows that the pi-orbitals along the stacking of base pairs can facilitate the long-range charge transfer in DNA. Proton motion in the base pair hydrogen bonds has also...

Carlson, E. W., Neto, A. H. Castro, Campbell, D. K.

In a type II superconductor in a moderate magnetic field, the superconductor to normal state transition may be described as a phase transition in which the vortex lattice melts into a liquid. In a...

A Coulomb gas approach to the anisotropic one-dimensional Kondo lattice model at arbitrary filling (2002)

Novais, E., Miranda, E., Neto, A. H. Castro, Cabrera, G. G.

We establish a mapping of a general spin-fermion system in one dimension into a classical generalized Coulomb gas. This mapping allows a renormalization group treatment of the anisotropic Kondo chain...

Stripe as an effective one-dimensional band of composite excitations (2002)

Chernyshev, A. L., White, S. R., Neto, A. H. Castro

The microscopic structure of a charge stripe in an antiferromagnetic insulator is studied within the t-Jz model using analytical and numerical approaches. We demonstrate that a stripe in an...

Charge Density Wave Formation in the Low-Temperature-Tetragonal Phase of Cuprates (2001)

Hasselmann, N., Neto, A. H. Castro, Smith, C. Morais

We calculate the influence of transverse fluctuations on the longitudinal dynamics in the striped phase of cuprates by using the bosonization technique. We find that a charge density wave instability...

Effect of impurities on quasi-2D quantum antiferromagnet (2001)

Chernyshev, A. L., Chen, Y. C., Neto, A. H. Castro

We have studied the static and dynamic properties of quasi-two-dimensional quantum antiferromagnets (AF) diluted with spinless impurities using spin-wave theory and $T$-matrix approximation. We show...

Charge Stripe in an Antiferromagnet: 1d Band of Composite Excitations (2001)

Chernyshev, A. L., White, Steven R., Neto, A. H. Castro

With the help of analytical and numerical studies of the $t$-$J_z$ model we argue that the charge stripe in an antiferromagnetic insulator should be understood as a system of holon-spin-polaron...

Diluted quantum antiferromagnets: spin excitations and long-range order (2001)

Chernyshev, A. L., Chen, Y. C., Neto, A. H. Castro

We have studied the static and dynamic magnetic properties of two-dimensional (2D) and quasi-two-dimensional, spin-S, quantum Heisenberg antiferromagnets (QHAF) diluted with spinless vacancies. Using...

Phase diagram of the anisotropic Kondo chain (2001)

Novais, E., Miranda, E., Neto, A. H. Castro, Cabrera, G. G.

We establish the phase diagram of the one-dimensional anisotropic Kondo lattice model at T=0 using a generalized two-dimensional classical Coulomb gas description. We analyze the problem by means of...

Non-linear excitations in 1D correlated insulators (2001)

$T_c$ suppression in co-doped striped cuprates (2000)

In this work we investigate charge transport in one-dimensional (1D) insulators via semi-classical and perturbative renormalization group (RG) methods. We consider the problem of electron-electron,...

Smith, C. Morais, Neto, A. H. Castro, Balatsky, A . V.

We propose a model that explains the reduction of $T_c$ due to the pinning of stripes by planar impurity co-doping in cuprates. A geometrical argument about the planar fraction of carriers affected...

Phonons and Solitons in 1D Mott Insulators (2000)

Smith, C. Morais, Hasselmann, N., Neto, A. H. Castro

We study the problem of one-dimensional (1D) Luttinger liquids in the insulating Mott-Hubbard phase in the presence of acoustic phonons in the semiclassical limit. We show that solitonic excitations...

We investigate the stripe pinning produced by Nd and Zn co-dopants in cuprates via a renormalization group approach. The two dopants play fundamentally different roles in the pinning process. While...

Long-range order and low-energy spectrum of diluted 2D quantum AF (2000)

Chernyshev, A. L., Chen, Y. C., Neto, A. H. Castro

The problem of diluted two-dimensional (2D) quantum antiferromagnet (AF) on a square lattice is studied using spin-wave theory. The influence of impurities on static and dynamic properties is...

Mutagenesis and Metallic DNA (2000)

Topological Defects and the Spin Glass Phase of Cuprates (2000)

Positions of protons in DNA hydrogen bonds are fundamental for the fidelity of the replication process. Because the hydrogen bond is partially covalent the electronic structure of DNA plays an...

Hasselmann, N., Neto, A. H. Castro, Smith, C. Morais

We propose that the spin glass phase of cuprates is due to the proliferation of topological defects of a spiral distortion of the antiferromagnet order. Our theory explains straightforwardly the...

Stripe dynamics in presence of disorder and lattice potentials (1999)

Smith, C. Morais, Hasselmann, N., Dimashko, Yu. A., Neto, A. H. Castro

We study the influence of disorder and lattice pinning on the dynamics of a charged stripe. Starting from a phenomenological model of a discrete quantum string, we determine the phase diagram for...

Charge ordering and long-range interactions in layered transition metal oxides: a quasiclassical continuum study (1999)

Stojkovic, Branko P., Yu, Z. G., Chernyshev, A. L., Bishop, A. R., Neto, A. H. Castro, Gronbech-Jensen, Niels

The competition between long-range and short-range interactions among holes moving in an antiferromagnet (AF), is studied within a model derived from the spin density wave picture of layered...

Non-Fermi liquid behavior in U and Ce intermetallics (1999)

One-Particle Spectral Properties of 1D Mott-Hubbard Insulators (1999)

In this paper we review the current experimental and theoretical situation of the description of non-Fermi liquid behavior (NFL) in U and Ce intermetallics. We focus on the magnetic and thermodynamic...

Carmelo, J. M. P., Guerra, J. M. E., Neto, A. H. Castro

We use an exact {\it holon} and {\it spinon} Landau-liquid functional which describes the holon - spinon interactions at all scattering orders, to study correlation functions of integrable...

Disorder-Driven Non-Fermi-Liquid Behavior in CeRhRuSi_2 (1999)

Liu, Chia-Ying, MacLaughlin, D. E., Neto, A. H. Castro, Lukefahr, H. G., Thompson, J. D., Sarrao, J. L., ...

We report measurements of the bulk magnetic susceptibility and ^{29}Si nuclear magnetic resonance (NMR) linewidth in the heavy-fermion alloy CeRhRuSi_2. The linewidth increases rapidly with...

Metallic stripe in two dimensions: stability and spin-charge separation (1999)

Chernyshev, A. L., Neto, A. H. Castro, Bishop, A. R.

The problems of charge stripe formation, spin-charge separation, and stability of the antiphase domain wall (ADW) associated with a stripe are addressed using an analytical approach to the t-J_z...

One-Particle Spectral Properties of Mott-Hubbard Insulators (1999)

Carmelo, J. M. P., Guerra, J. M. E., Neto, A. H. Castro

We use an exact holon and spinon Landau-liquid functional which describes the holon - spinon interactions at all scattering orders, to study correlation functions of integrable multicomponent...

Effective Field Theory for Layered Quantum Antiferromagnets with Non-Magnetic Impurities (1999)

Chen, Y. C., Neto, A. H. Castro

We propose an effective two-dimensional quantum non-linear sigma model combined with classical percolation theory to study the magnetic properties of site diluted layered quantum antiferromagnets...

Mobility of Bloch Walls via the Collective Coordinate Method (1999)

Despósito, M. A., Ferrer, A. Villares, Caldeira, A. O., Neto, A. H. Castro

We have studied the problem of the dissipative motion of Bloch walls considering a totally anisotropic one dimensional spin chain in the presence of a magnetic field. Using the so-called "collective...

The Striped Phase in Presence of Disorder and Lattice Potentials (1998)

Hasselmann, N., Neto, A. H. Castro, Smith, C. Morais, Dimashko, Y.

We study the influence of disorder and lattice effects on the striped phase and the incommensurate spin fluctuations of the cuprates and nickelates. Starting from a phenomenological model of a...

Charge ordering and long-range interactions in layered transition metal oxides (1998)

Stojkovic, Branko P., Yu, Z. G., Bishop, A. R., Neto, A. H. Castro, Gronbech-Jensen, Niels

We study the competition between long-range and short-range interactions among holes within the spin density wave picture of layered transition metal oxides. We focus on the problem of charge...

Effect of planar impurities on the superfluid density of striped cuprates (1998)

Neto, A. H. Castro, Balatsky, A. V.

We propose a mechanism for superconductivity suppression in stripe-correlated cuprates based on the pinning of the stripes by impurities, such as Zn. The suppression of superfluid density occurs in...

Evidence for a common physical description of non-Fermi-liquid behavior in f-electron systems (1998)

De Andrade, M. C., Chau, R., Dickey, R. P., Dilley, N. R., Freeman, E. J., Gajewski, D. A., ...

The non-Fermi-liquid (NFL) behavior observed in the low temperature specific heat $C(T)$ and magnetic susceptibility $\chi(T)$ of f-electron systems is analyzed within the context of a recently...

Non-Fermi liquid behavior and Griffiths phase in {\it f}-electron compounds (1997)

Neto, A. H. Castro, Castilla, G., Jones, B. A.

We study the interplay among disorder, RKKY and Kondo interactions in {\it f}-electron alloys. We argue that the non-Fermi liquid behavior observed in these systems is due to the existence of a...

Superconductivity, Josephson coupling and order parameter symmetry in striped cuprates (1997)

Neto, A. H. Castro, Guinea, F.

We consider a renormalization group study of the problem of coupled stripes of holes in cuprates. We use a model of a mesh of horizontal and vertical stripes and study the problemof superconductivity...

Open Luttinger liquids (1997)

Neto, A. H. Castro, Chamon, C. De C., Nayak, C.

We study the problem of Luttinger liquids interacting with an active environment. We are particularly interested in how dissipation affects the response and correlation functions of non-isolated...

Theory of Spin Fluctuations in Striped Phases of Doped Antiferromagnetic Cuprates (1997)

Hone, Daniel, Neto, A. H. Castro

We study the properties of generalized striped phases of doped cuprate planar quantum antiferromagnets. We invoke an effective, spatially anisotropic, non-linear sigma model in two space dimensions....

Luttinger Stripes in Antiferromagnets (1996)

Landau level bosonization of a 2D electron gas (1996)

We propose a model for the physics of stripes in antiferromagnets in which the stripes are described by Luttinger liquids hybridized with antiferromagnetic domains. Using bosonization techniques we...

Westfahl Jr., H., Neto, A. H. Castro, Caldeira, A. O.

In this work we introduce a bosonization scheme for the low energy excitations of a 2D interacting electron gas in the presence of an uniform magnetic field under conditions where a large integral...

Magnetic-field and chemical-potential effects on the low-energy separation (1996)

Carmelo, J. M. P., Neto, A. H. Castro

We show that in the presence of a magnetic field the usual low-energy separation of the Hubbard chain is replaced by a ``$c$'' and ``$s$'' separation. Here $c$ and $s$ refer to small-momentum and...

Electrons, pseudoparticles, and quasiparticles in the one-dimensional many-electron problem (1996)

Carmelo, J. M. P., Neto, A. H. Castro

We generalize the concept of quasiparticle for one-dimensional (1D) interacting electronic systems. The $\uparrow $ and $\downarrow $ quasiparticles recombine the pseudoparticle colors $c$ and $s$...

Doped planar quantum antiferromagnets with striped phases (1995)

Neto, A. H. Castro, Hone, Daniel

We study the properties of the striped phases that have been proposed for the doped cuprate planar quantum antiferromagnets. We invoke an effective, spatially anisotropic, non-linear sigma model in...

Dynamics of a heavy particle in a Luttinger liquid (1995)

Neto, A. H. Castro, Fisher, Matthew P. A.

We study the dynamics of a heavy particle of mass $M$ moving in a one-dimensional repulsively interacting Fermi gas. The Fermi gas is described using the Luttinger model and bosonization. By...

Electrons, pseudoparticles, and quasiparticles in one-dimensional interacting electronic systems (1995)

Carmelo, J. M. P., Neto, A. H. Castro, Peres, N. M. R.

We find the singular transformation between the electron operator and the pseudoparticle operators for the Hubbard chain. We generalize the concept of quasiparticle to one-dimensional electronic...

On a class of integrable interacting electronic systems with off-diagonal disorder (1995)

Neto, A. H. Castro, Campbell, D. K., Phillips, Philip

We report a class of {\it integrable} one-dimensional interacting electronic sy$ with {\it off-diagonal disorder}. For these systems, the disorder can be ``gauged away,''and the spectrum can be...

Motion of heavy particles coupled to fermionic and bosonic environments in one dimension (1995)

Caldeira, A. O., Neto, A. H. Castro

Making use of a simple unitary transformation we change the hamiltonian of a particle coupled to an one dimensional gas of bosons or fermions to a new form from which the many body degrees of freedom...

Non-Linear Waves in Fermi Liquids (1994)

Landau theory of phase separation in cuprates (1994)

I show that when non-linearities are taken into account the Landau theory of Fermi liquids predicts the existence of hyperbolic waves in fermionic systems. The zero sound is described by a infinite...

Pseudoparticle-operator description of an interacting Bose gas (1994)

I discuss the problem of phase separation in cuprates from the point of view of the Landau theory of Fermi liquids. I calculate the rate of growth of unstable regions for the hydrodymanics and...

Neto, A. H. Castro, Lin, H. Q., Carmelo, J. M. P.

We write the Hamiltonian of the Bose gas with two-body repulsive $\delta$-function potential in a pseudoparticle operator basis which diagonalizes the problem via the Bethe ansatz. In this operator...

Conservation laws and bosonization in integrable Luttinger liquids (1994)

Carmelo, J. M. P., Neto, A. H. Castro, Campbell, D. K.

We examine and explain the Luttinger-liquid character of models solvable by the Bethe ansatz by introducing a suitable bosonic operator algebra. In the case of the Hubbard chain, this involves two...

New perturbation theory of low-dimensional quantum liquids I: the pseudoparticle operator basis (1994)

Carmelo, J. M. P., Neto, A. H. Castro, Campbell, D. K.

We introduce a new operator algebra for the description of the low-energy physics of one-dimensional, integrable, multicomponent quantum liquids. Considering the particular case of the Hubbard chain...

New perturbation theory of low-dimensional quantum liquids II: operator description of Virasoro algebras in integrable systems (1994)

Carmelo, J. M. P., Neto, A. H. Castro, Campbell, D. K.

We show that the recently developed {\it pseudoparticle operator algebra} which generates the low-energy Hamiltonian eigenstates of multicomponent integrable systems also provides a natural operator...

The mobility and diffusion of a particle coupled to a Luttinger liquid (1994)

Exact solution of the Landau fixed point via bosonization (1993)

We study the mobility of a particle coupled to a one dimensional interacting fermionic system, a Luttinger liquid. We bosonize the Luttinger liquid and find the effective interaction between the...

Neto, A. H. Castro, Fradkin, Eduardo H.

We study, via bosonization, the Landau fixed point for the problem of interacting spinless fermions near the Fermi surface in dimensions higher than one. We rederive the bosonic representation of the...

Dissipative quantum systems modeled by a two level reservoir coupling (1993)

Caldeira, A. O., Neto, A. H. Castro, De Carvalho, T. Oliveira

The coupling between a quantum dynamical system and a two-level system reservoir is analysed within the framework of the Feynman-Vernon theory. We stress the differences between this new reservoir...

Bosonization of Fermi liquids (1993)

Neto, A. H. Castro, Fradkin, Eduardo

We bosonize a Fermi liquid in any number of dimensions in the limit of long wavelengths. From the bosons we construct a set of coherent states which are related with the displacement of the Fermi...

On Quantum Scattering of a System with Internal Degrees of Freedom (1993)

Transport Properties of Solitons (1993)

We study the quantum tunnelling of a very complex object of which only part is coupled to an external potential ( the potential barrier ). We treat this problem as the tunnelling of a particle (part...

Bosonization of the Low Energy Excitations of Fermi Liquids (1993)

We calculate in this article the transport coefficients which characterize the dynamics of solitons in quantum field theory using the methods of dissipative quantum systems. We show how the damping...

Neto, A. H. Castro, Fradkin, Eduardo

We bosonize the low energy excitations of Fermi Liquids in any number of dimensions in the limit of long wavelengths. The bosons are coherent superposition of electron-hole pairs and are related with...

Dynamical decoupling and Kac-Moody current representation in multicomponent integrable systems (1993)

Carmelo, J. M. P., Neto, A. H. Castro

The conformal invariant character of $\nu$-multicomponent integrable systems (with $\nu$ branches of gapless excitations) is described from the point of view of the response to curvature of the...

The Thermodynamics of Quantum Systems and Generalizations of Zamolodchikov's C-theorem (1993)

Neto, A. H. Castro, Fradkin, Eduardo

In this paper we examine the behavior in temperature of the free energy on quantum systems in an arbitrary number of dimensions. We define from the free energy a function $C$ of the coupling...

An alternative approach for the dynamics of polarons in one dimension (1992)