Dmitrii Maslov - Academia.edu (original) (raw)

Papers by Dmitrii Maslov

The spin of electrons in a semiconductor environment couples not only to magnetic ﬁelds, but also... more The spin of electrons in a semiconductor environment couples not only to magnetic ﬁelds, but also to the orbital motion of the electron. As a consequence, transport in semiconductors includes a class of phenomena in which electrically induced charge motion inﬂuences the electron spin. The intricate interplay of spin and charge makes this type of eﬀects a diverse research ﬁeld of fundamental interest, but is also of practical relevance: Spin-orbit interaction (SOI) provides a mechanism to control the spin with electric ﬁelds. Being available in tailored materials, that are routinely used in microelectronics, SOI has therefore attracted intense interest for its potential in applications to use the electron spin alternatively to the charge in new types of electronic devices. In this thesis we investigate the interplay of spin and charge transport in disordered electron systems, where random impurities not only determine the electrical resistance but also the spin dynamics through spin-...

Physical Review Letters, 1993

We study mesoscopic conductance fluctuations in the metallic phase of the integer quantum Hall ef... more We study mesoscopic conductance fluctuations in the metallic phase of the integer quantum Hall effect. We derive effective boundary conditions for the diffuson propagator which incorporate the edge-state transport along the sample boundaries. It is shown that the presence of edge states leads to a resonance structure in the conductance fluctuations which occurs as the Fermi level moves across the band of extended states. The result of this analytic treatment is consistent with that of our numerical simulations and can be tested experimentally.

Physical Review B, 2012

We analyze the ordered state of nuclear spins embedded in an interacting two-dimensional electron... more We analyze the ordered state of nuclear spins embedded in an interacting two-dimensional electron gas (2DEG) with Rashba spin-orbit interaction (SOI). Stability of the ferromagnetic nuclear-spin phase is governed by nonanalytic dependences of the electron spin susceptibility χ ij on the momentum (q) and on the SOI coupling constant (α). The uniform (q = 0) spin susceptibility is anisotropic (with the out-of-plane component, χ zz , being larger than the in-plane one, χ xx , by a term proportional to U 2 (2kF)|α|, where U (q) is the electron-electron interaction). Forq ≤ 2m * |α|, corrections to the leading, U 2 (2kF)|α|, term scale linearly withq for χ xx and are absent for χ zz. This anisotropy has important consequences for the ferromagnetic nuclear-spin phase: (i) the ordered state-if achieved-is of an Ising type and (ii) the spin-wave dispersion is gapped atq = 0. To second order in U (q), the dispersion a decreasing function ofq, and anisotropy is not sufficient to stabilize long-range order. However, renormalization in the Cooper channel forq ≪ 2m * |α| is capable of reversing the sign of theq-dependence of χ xx and thus stabilizing the ordered state. We also show that a combination of the electron-electron and SO interactions leads to a new effect: long-wavelength Friedel oscillations in the spin (but not charge) electron density induced by local magnetic moments. The period of these oscillations is given by the SO length π/m * |α|.

Quantum Dynamics of Submicron Structures, 1995

Since the work of Buttiker et al. [1] persistent currents have attracted much recent interest bot... more Since the work of Buttiker et al. [1] persistent currents have attracted much recent interest both theoretically [2, 3, 4, 5, 6, 7, 8, 9, 10] and experimentally [11]. We shall present here a theoretical work on the general effect of interactions on persistent currents in one-dimensional (1D) rings of mesoscopic size in a phase coherent state. We shall assume that the system is sufficiently clean so that we can neglect disorder effects on the length scale of a few microns. Such a situation is approximately found in heterojunctions (see Mailly et al. [11]). We start with a brief discussion of the free case. Then, turning to the interacting system we give some general arguments demonstrating that even in translationally invariant systems the persistent current is affected by interactions. Using bosonization and renormalization group techniques we derive the Luttinger liquid fixed point and calculate the persistent current first in the ground state, but also determine its finite temperature and finite size corrections. Another aspect of this work is to show that the remarkable parity effects known from the free case[12] also occur in the presence of interactions[13, 6].

Physical Review B, 2007

We report measurements of the spin susceptibility in dilute (rs up to ≈ 10) AlAs two-dimensional ... more We report measurements of the spin susceptibility in dilute (rs up to ≈ 10) AlAs two-dimensional (2D) electrons occupying a single conduction-band valley with an anisotropic in-plane Fermi contour, characterized by longitudinal and transverse effective masses, m l and mt. As the density is decreased, the spin susceptibility is significantly enhanced over its band value, reflecting the role of interaction. Yet the enhancement is suppressed compared to the results of quantum Monte Carlo based calculations that take the finite thickness of the electron layer into account but assume an isotropic effective mass equal to √ m l .mt. Proper treatment of an interacting 2D system with an anisotropic effective mass therefore remains a theoretical challenge.

In addition to charge plasmons, a 2D electron system with Rashba-type spin-orbit coupling (SOC) a... more In addition to charge plasmons, a 2D electron system with Rashba-type spin-orbit coupling (SOC) also supports three collective modes in the spin sector: the chiral-spin modes. We study the dispersions of the charge and spin modes and their coupling to each other within a generalized Random Phase Approximation for arbitrarily strong SOC, and both in 2D and 3D systems. In both 2D and 3D, we find that the charge plasmons are coupled to only one of the three chiral-spin modes. This coupling is shown to affect the dispersions of the modes at finite but not at zero wavenumbers. In 3D, the chiral-spin modes are strongly damped by particle-hole excitations and disappear for weak electron-electron interaction. Landau damping of the chiral-spin modes in 3D is directly related to the fact that, in contrast to 2D, there is no gap for particle-hole excitations between spin-split subbands. The gapless continuum is also responsible for Landau damping of the charge plasmon in 3D-a qualitatively new feature of the SOC system. We also discuss the optical conductivity of clean 2D and 3D systems and show that SOC introduces spectral weight at finite frequency in a such way that the sum rule is satisfied. The in-plane tranverse chiral-spin mode shows up as dispersing peak in the optical conductivity at finite number which can can be measured in the presence of diffraction grating. We also discuss possible experimental manifestations of chiral-spin modes in semiconductor quantum wells such InGaAs/AlGaAs and 3D giant Rashba materials of the BiTeI family.

The recent study of the RKKY interaction between localized moments, e.g., nuclear spins of Ga and... more The recent study of the RKKY interaction between localized moments, e.g., nuclear spins of Ga and As atoms in a GaAs heterostructure, mediated by interacting two-dimensional electrons, has shown a possibility of polarizing nuclear spins at currently accessible temperatures [1]. This ferromagnetic phase transition is governed by: (i) anisotropy of the electron spin susceptibility, chi, in the presence of Rashba

Phys Rev Lett, 1999

It is shown that recent experiments indicating a metal-insulator transition in 2D electron system... more It is shown that recent experiments indicating a metal-insulator transition in 2D electron systems can be interpreted in terms of a simple model, in which the resistivity is controlled by scattering at charged hole traps located in the oxide layer. The gate voltage changes the number of charged traps which results in a sharp change in the resistivity. The observed exponential temperature dependence of the resistivity in the metallic phase of the transition follows from the temperature dependence of the trap occupation number. The model naturally describes the experimentally observed scaling properties of the transition and the effects of magnetic and electric fields.

Physical Review B Condensed Matter and Materials Physics, 2006

We revisit the issue of the leading nonanalytic corrections to the temperature dependence of the ... more We revisit the issue of the leading nonanalytic corrections to the temperature dependence of the specific heat coefficient, γ(T)=C(T)/T , for a system of interacting fermions in three dimensions. We show that the leading temperature dependence of the specific heat coefficient γ(T)-γ(0)∝T3lnT comes from two physically distinct processes. The first process involves a thermal excitation of a single particle-hole pair, whose components interact via a nonanalytic dynamic vertex. The second process involves an excitation of three particle-hole pairs which interact via the analytic static fixed-point vertex. We show that the single-pair contribution is expressed via the backscattering amplitude of quasiparticles at the Fermi surface. The three-pair contribution does not have a simple expression in terms of scattering in particular directions. We clarify the relation between these results and previous literature on both 3D and 2D systems, and discuss the relation between the nonanalyticities in γ and those in spin susceptibilities.

Physical Review B Condensed Matter, Jul 1, 1993

We consider transport through ballistic conductors connected to disordered reservoirs. These syst... more We consider transport through ballistic conductors connected to disordered reservoirs. These systems are shown to exhibit a filtering effect: the insertion of the ballistic constriction into the disordered conductor reduces the effects of the disorder. For the case of quasiballistic transport in the disordered regions an analytic model based on the transfer-matrix formalism is developed. It shows that the suppression of the conductance fluctuations is much weaker than that predicted by Ohm's law for a network of classical resistors in series. The results of the analytic model agree well with those of numerical simulations carried out using the recursive Green's-function technique. The numerical simulations show that when the disorded regions are in the diffusive regime, the suppression of the disorder effects is still present, though it is weaker than in the case of quasiballistic transport.

Aps March Meeting Abstracts, Mar 1, 1996

We introduce and investigate a new class of chaotic billiards---Andreev billiards---in which a no... more We introduce and investigate a new class of chaotic billiards---Andreev billiards---in which a normal region is surrounded by a superconducting region.(I. Kosztin, D. Maslov, P. M. Goldbart, Phys. Rev. Lett. 75) (1995) 1735. In contrast with previously studied billiards, Andreev billiards are classically integrable in the absence of a magnetic field, regardless of their shape, owing to the retro-reflective character of the Andreev reflection process that occurs at the normal-superconductor interface. In the presence of a magnetic field, integrable classical motion in a generically shaped Andreev billiard is transformed into chaotic motion. We analyze the development of magnetic-field--induced classical chaos for the case of Bunimovich-stadium--shaped Andreev billiards by using the tangent map technique. Thus we are able to to examine the morphologies of Poincaré sections and Lyapunov exponents, the positivity of which signal the exponential sensitivity of trajectories to initial conditions. We also address certain quantum-mechanical implications of this magnetic-field--induced classical chaos, and review the feasibilty of certain candidate settings for realizing Andreev billiards experimentally.

Physica B: Condensed Matter, 2002

Physical Review B, 1998

Reflection of charge excitations at the step in the interaction strength in a Luttinger liquid ca... more Reflection of charge excitations at the step in the interaction strength in a Luttinger liquid can be of the Andreev type, even the interactions are purely repulsive. The region with stronger repulsion plays the role of a normal metal in a normal-metal/superconductor junction, whereas the region with weaker repulsion plays the role of a superconductor. It is shown that this quasi-Andreev reflection leads to a number of proximity-like effects, including the local enhancement (suppression) of superconducting fluctuations on the quasi-normal (quasi-superconducting) side of the step, significant modification of the local density of states, as well as others. The observable consequences of these proximity effects are analyzed for the case of single-and two-particle tunneling from a normal-metal or superconducting tip into an inhomogeneous Luttinger-liquid wire.

Physical Review B, 2001

Magnetotransport has been investigated in high-purity bismuth crystals in static magnetic fields ... more Magnetotransport has been investigated in high-purity bismuth crystals in static magnetic fields as high as 20 T and temperatures as low as 25 mK. This high B/T ratio permits observation of pronounced Shubnikov-de Haas oscillations over a wide field range and up to fields where most of the carriers are in the lowest Landau level. For transport currents in the bisectrix or binary directions, and field in the perpendicular trigonal direction, we have observed doublet splittings centered on each Shubnikov-de Haas oscillation. These splittings exhibit a quadratic dependence on field and disappear before the last oscillation. Our observations allow us to conclude unambiguously that when the Landau-level index is as high as 2, the carriers are fully polarized and the g factor for holes with the field in the trigonal direction is 35.3͑4͒.

Magneto transport data have been obtained for high purity bismuth crystals with various orientati... more Magneto transport data have been obtained for high purity bismuth crystals with various orientations in fields B as high as 20T and temperatures as low as 25mK. For fields on the order of 15T in the trigonal direction we find, in agreement with theoretical expectations, that all holes are in the lowest Landau level. More than twenty-five Shubnikov de Haas

Lecture Notes in Physics, 2000

We investigate possible nontrivial phases of a two-subband quantum wire. It is found that interan... more We investigate possible nontrivial phases of a two-subband quantum wire. It is found that interand intra-subband interactions may drive the electron system of the wire into a gapped state. If the nominal electron densities in the two subbands are sufficiently close to each other, then the leading instability is the inter-subband charge-density wave (CDW). For large density imbalance, the interaction in the inter-subband Cooper channel may lead to a superconducting instability. The total charge-density mode, responsible for the conductance of an ideal wire, always remains gapless, which enforces the two-terminal conductance to be at the universal value of 2e 2 /h per occupied subband. On the contrary, the tunneling density of states (DOS) in the bulk of the wire acquires a hard gap, above which the DOS has a non-universal singularity. This singularity is weaker than the square-root divergency characteristic for non-interacting quasiparticles near a gap edge due to the "dressing" of massive modes by a gapless total charge density mode. The DOS for tunneling into the end of a wire in a CDW-gapped state preserves the power-law behavior due to the frustration the edge introduces into the CDW order. This work is related to the vast literature on coupled 1D systems, and most of all, on two-leg Hubbard ladders. Whenever possible, we give derivations of the important results by other authors, adopted for the context of our study.

It is shown, within the framework of the Ginzburg-Landau theory for a superconductor with d x 2 −... more It is shown, within the framework of the Ginzburg-Landau theory for a superconductor with d x 2 −y 2 symmetry, that the passing of a supercurrent through the sample results, in general, in the induction of order-parameter components of distinct symmetry. The induction of s-wave and d xy(x 2 −y 2 )wave components are considered in detail. It is shown that in both cases the order parameter remains gapless; however, the structure of the lines of nodes and the lobes of the order parameter are modified in distinct ways, and the magnitudes of these modifications differ in their dependence on the (a-b plane) current direction. The magnitude of the induced s-wave component is estimated using the results of the calculations of Ren et al. [Phys. Rev. Lett. 74, 3680 (1995)], which are based on a microscopic approach.

Physical Review B, 1996

A theory describing a one-dimensional Luttinger liquid in contact with superconductor is develope... more A theory describing a one-dimensional Luttinger liquid in contact with superconductor is developed. Boundary conditions for the fermion fields describing Andreev reflection at the contacts are derived and used to construct a bosonic representation of the fermions. The Josephson current through a superconductor/Luttinger liquid/superconductor junction is considered for both perfectly and poorly transmitting interfaces. In the former case, the Josephson current at low temperatures is found to be essentially unaffected by electron-electron interactions. In the latter case, significant renormalization of the Josephson current occurs. The profile of the (induced) condensate wavefunction in a semiinfinite Luttinger liquid in contact with a superconductor is shown to decay as a power-law, the exponent depending on the sign and strength of the interactions. In the case of repulsive (attractive) interactions the decay is faster (slower) than in their absence. An equivalent method of calculating the Josephson current through a Luttinger liquid, which employs the bosonization of the system as a whole (i.e., superconductor, as well as Luttinger liquid) is developed and shown to give the results equivalent to those obtained via boundary conditions describing Andreev reflection.