arXiv subjects

Victor M. Yakovenko

Publications and source records attributed to Victor M. Yakovenko.

86 records · Page 5Linked to original sources

arXiv1998

Magnetic-field-induced Luttinger insulator state in quasi-one-dimensional conductors

We present a heuristic, semiphenomenological model of the anomalous temperature (T) dependence of resistivity $ρ_{xx}$ recently observed experimentally in the quasi-one-dimensional (Q1D) organic conductors of the (TMTSF)2X family in moderately strong magnetic fields. We suggest that a Q1D conductor behaves like an insulator ($dρ_{xx}/dT<0$), when its effective dimensionality is one, and like a metal ($dρ_{xx}/dT>0$), when its effective dimensionality is greater than one. Applying a magnetic field reduces the effective dimensionality of the system and switches the temperature dependence of resistivity between the insulating and metallic laws depending on the magnitude of the magnetic field and its orientation along the ``magic'' and ``nonmagic'' angles.

cond-mat.str-el↗

arXiv1998

Edge and bulk electron states in a quasi-one-dimensional metal in a magnetic field: The semi-infinite Wannier-Stark ladder

We study edge and bulk open-orbit electron states in a quasi-one-dimensional (Q1D) metal subject to a magnetic field. For both types of the states, the energy spectrum near the Fermi energy consists of two terms. One term has a continuous dependence on the momentum along the chains, whereas the other term is quantized discretely. The discrete energy spectrum is mathematically equivalent to the Wannier-Stark energy ladder of a semi-infinite 1D lattice in an effective electric field. We solve the latter problem analytically in the semiclassical approximation and by numerical diagonalization. We show explicitly that equilibrium electric currents vanish both at the edges and in the bulk, so no orbital magnetization is expected in a Q1D metal in a magnetic field.

cond-mat.mes-hall↗

arXiv1997

Sign reversals of the quantum Hall effect and helicoidal magnetic-field-induced spin-density waves in quasi-one-dimensional organic conductors

We study the effect of umklapp scattering on the magnetic-field-induced spin-density-wave phases, which are experimentally observed in the quasi-one-dimensional organic conductors of the Bechgaard salts family. Within the framework of the quantized nesting model, we show that umklapp processes may naturally explain sign reversals of the quantum Hall effect (QHE) observed in these conductors. Moreover, umklapp scattering can change the polarization of the spin-density wave (SDW) from linear (sinusoidal SDW) to circular (helicoidal SDW). The QHE vanishes in the helicoidal phases, but a magnetoelectric effect appears. These two characteristic properties may be utilized to detect the magnetic-field-induced helicoidal SDW phases experimentally.

cond-mat↗

arXiv1997

Phenomenological interpretations of the ac Hall effect in the normal state of YBa2Cu3O7

Ac and dc magnetotransport data in the normal state of YBa2Cu3O7 are analyzed within Fermi-liquid and non-Fermi-liquid models. In the Fermi-liquid analysis we use the Fermi surface deduced from band structure calculations and angular resolved photoemission experiments and assume that the electron relaxation rate varies over the Fermi surface. The non-Fermi-liquid models are the two-dimensional Luttinger liquid model and the charge-conjugation-symmetry model. We find that the existing experimental data can be adequately fitted by any of these models. This work provides a framework for the analysis of experiments that may discriminate among these models.

cond-mat.supr-con↗

arXiv1997

Spin, Statistics and Charge of Solitons in (2+1)-Dimensional Theories

General topologically invariant microscopical expressions for quantum numbers of particle-like solitons ("skyrmions") are derived for a class of (2+1)D models. Skyrmions are either half-integer spin fermions with odd electric charge or integer spin bosons with even charge. So they cannot be Anderson's spinons or holons. General results are exemplified by a square lattice model reminiscenting high-Tc models.

cond-mat.str-el↗

arXiv1997

Quantum Hall Effect in Quasi-One-Dimensional Conductors: The Roles of Moving FISDW, Finite Temperature, and Edge States

This paper reviews recent developments in the theory of the quantum Hall effect (QHE) in the magnetic-field-induced spin-density-wave (FISDW) state of the quasi-one-dimensional organic conductors (TMTSF)$_2$X. The origin and the basic features of the FISDW are reviewed. The QHE in the pinned FISDW state is derived in several simple, transparent ways, including the edge states formulation of the problem. The temperature dependence of the Hall conductivity is found to be the same as the temperature dependence of the Fröhlich current. It is shown that, when the FISDW is free to move, it produces an additional contribution to the Hall conductivity that nullifies the total Hall effect. The paper is written on mathematically simple level, emphasizes physical meaning over sophisticated mathematical technique, and uses inductive, rather than deductive, reasoning.

cond-mat↗

arXiv1996

Parquet solution for a flat Fermi surface

We study instabilities occurring in the electron system whose Fermi surface has flat regions on its opposite sides. Such a Fermi surface resembles Fermi surfaces of some high-$T_c$ superconductors. In the framework of the parquet approximation, we classify possible instabilities and derive renormalization-group equations that determine the evolution of corresponding susceptibilities with decreasing temperature. Numerical solutions of the parquet equations are found to be in qualitative agreement with a ladder approximation. For the repulsive Hubbard interaction, the antiferromagnetic (spin-density-wave) instability dominates, but when the Fermi surface is not perfectly flat, the $d$-wave superconducting instability takes over.

cond-mat↗

arXiv1996

Temperature Evolution of the Quantum Hall Effect in Quasi-One-Dimensional Organic Conductors

The Hall conductivity in the magnetic-field-induced spin-density-wave (FISDW) state of the quasi-one-dimensional organic conductors (TMTSF)$_2$X at a finite temperature is calculated. The temperature dependence of the Hall conductivity is found to be the same as the temperature dependence of the Fröhlich current of a regular charge/spin-density wave. Predicted dependence $σ_{xy}(T)$ can be verified experimentally in the (TMTSF)$_2$X compounds if all components of the resistivity tensor are measured and the conductivity tensor is reconstructed.

cond-mat↗

arXiv1996

Neutron scattering and superconducting order parameter in YBa2Cu3O7

We discuss the origin of the neutron scattering peak at 41 meV observed in YBa$_2$Cu$_3$O$_7$ below $T_c$. The peak may occur due to spin-flip electron excitations across the superconducting gap which are enhanced by the antiferromagnetic interaction between Cu spins. In this picture, the experiment is most naturally explained if the superconducting order parameter has $s$-wave symmetry and opposite signs in the bonding and antibonding electron bands formed within a Cu$_2$O$_4$ bilayer.

cond-mat↗

arXiv1995

What happens to the quantum Hall effect when magnetic-field-induced spin-density wave moves

The influence of the motion of a magnetic-field-induced spin-density wave (FISDW) on the quantum Hall effect in a quasi-one-dimensional conductor is studied theoretically. In the ideal case of a free FISDW, it is found that the counterflow of the FISDW precisely cancels the quantum Hall current, so the resultant Hall conductivity is zero. In real systems, the Hall conductivity should vanish at the high frequencies, where the pinning and the damping can be neglected, and the dynamics of the FISDW is dominated by inertia.

cond-mat↗

arXiv1995

``Hot Spots'' in Quasi-One-Dimensional Organic Conductors

Distribution of the electron scattering rate on the Fermi surface of a quasi-one-dimensional conductor is calculated for the electron-electron umklapp interaction. We find that in certain regions on the Fermi surface the scattering rate is anomalously high. The reason for the existence of these ``hot spots'' is analogous to the appearance of the van Hove singularities in the density of states. We employ a generalized $τ$-approximation (where the scattering integral in the Boltzmann equation is replaced by the scattering time which depends on the position at the Fermi surface) to study the dependence of the electric resistance on the amplitude and the orientation of a magnetic field. We find that the ``hot spots'' do not produce a considerable magnetoresistance or commensurability effects at the so-called ``magic angles''.

cond-mat↗

arXiv1993

Once again about interchain hopping

Renormalization group equations and a phase diagram are derived for a system of two chains with a single-electron hopping between chains in order to correct the results of a recent paper by F.~V.~Kusmartsev, A.~Luther, and A.~Nersesyan, Pis'ma v Zh.\ Exp.\ Teor.\ Fiz.\ {\bf 55}, 692 (1992) [JETP Lett.\ {\bf 55}, 724 (1992)].

cond-mat↗

arXiv1992

Metals in high magnetic field: a new universality class of Fermi liquids

Parquet equations, describing the competition between superconducting and density-wave instabilities, are solved for a three-dimensional isotropic metal in a high magnetic field when only the lowest Landau level is filled. In the case of a repulsive interaction between electrons, a phase transition to the density-wave state is found at finite temperature. In the opposite case of attractive interaction, no phase transition is found. With decreasing temperature $T$, the effective vertex of interaction between electrons renormalizes toward a one-dimensional limit in a self-similar way with the characteristic length (transverse to the magnetic field) decreasing as $\ln^{-1/6}(ω_c/T)$ ($ω_c$ is a cutoff). Correlation functions have new forms, previously unknown for conventional one-dimensional or three-dimensional Fermi-liquids.

cond-mat↗

arXiv1992

Theory of Thermodynamic Magnetic Oscillations in Quasi-One-Dimensional Conductors

The second order correction to free energy due to the interaction between electrons is calculated for a quasi-one-dimensional conductor exposed to a magnetic field perpendicular to the chains. It is found that specific heat, magnetization and torque oscillate when the magnetic field is rotated in the plane perpendicular to the chains or when the magnitude of magnetic filed is changed. This new mechanism of thermodynamic magnetic oscillations in metals, which is not related to the presence of any closed electron orbits, is applied to explain behavior of the organic conductor (TMTSF)$_2$ClO$_4$.

cond-mat↗