Showing papers by "Yoseph Imry published in 1995"
TL;DR: In this paper, a physical consideration is given to reinforce, interpret and generalize the result of Shepelyansky that a not too weak short-range interaction can cause correlated two-electron states to be substantially delocalized with respect to singleelectron ones.
Abstract: A physical consideration is given to reinforce, interpret and generalize the result of Shepelyansky that a not too weak short-range interaction can cause correlated two-electron states to be substantially delocalized with respect to single-electron ones. A generalization of the Thouless block-scaling picture is used and its wide applicability is pointed out. A similar effect for correlated electron-hole pairs is also found. Some physical applications are briefly discussed.
88 citations
TL;DR: It is argued that for strictly dc conditions, the transport quantity that should be averaged is the resistivity, and when the Hall resistivity is derived from the averaged conductivity, the resulting temperature dependence is sensitive to the disorder configuration.
Abstract: The Hall conductivity and resistivity of strongly localized electrons at low temperatures and at small magnetic fields are obtained. It is found that the results depend on whether the conductivity or the resistivity tensors are averaged to obtain the macroscopic Hall resistivity. In the second case the Hall resistivity always {\it diverges} exponentially as the temperature tends to zero. But when the Hall resistivity is derived from the averaged conductivity, the resulting temperature dependence is sensitive to the disorder configuration. Then the Hall resistivity may approach a constant value as $T\to 0$. This is the Hall insulating behavior. It is argued that for strictly dc conditions, the transport quantity that should be averaged is the resistivity.
23 citations
TL;DR: In this paper, the authors used the conventional scaling approach as well as the renormalization group analysis in d = 2 + e dimensions to calculate the localization length ξ(B) in the presence of a magnetic field B.
Abstract: Using the conventional scaling approach as well as the renormalization group analysis in d = 2 + e dimensions, we calculate the localization length ξ(B) in the presence of a magnetic field B. For the quasi-1D case the results are consistent with a universal increase of ξ(B) by a numerical factor when the magnetic field is in the range l lH ξ(0), l is the mean free path, lH is the magnetic length √c/eB. However, for d ≥ 2 where the magnetic field does cause delocalization there is no universal relation between ξ(B) and ξ(0). The effect of spin-orbit interaction is briefly considered as well.
15 citations
TL;DR: The orbital magnetic moment of localized electrons is considered, both in the absence and in the presence of the electron-phonon interaction, and for the isolated electronic system the magnetic moment has a definite sign which alternates as the location of the Fermi level is varied.
Abstract: The orbital magnetic moment of localized electrons is considered, both in the absence and in the presence of the electron-phonon interaction. This magnetic moment, proportional to the persistent current circulating around groups of at least three localized states, arises from interference of the localized electronic wave functions. It is shown that for the isolated electronic system the magnetic moment has a definite sign which alternates as the location of the Fermi level is varied. When the electrons are coupled to the thermal bath, the orbital magnetic moment decreases due to two effects: (i) the appearance of a current that flows in the opposite direction to that of the isolated system\char22{}this countercurrent results from resonant electron-phonon processes, suggested by Holstein; (ii) an overall Debye-Waller factor that diminishes the magnitude of the orbital response to the external magnetic field. A possible experimental realization to observe the countercurrent is discussed.
14 citations
TL;DR: In this paper, the authors considered tunnelling across a p-n junction (a diode) where the motion on both sides is constrained by quantum wells (QW) in the direction perpendicular to the interface to form 2D n-type and p-type electron gases.
Abstract: We consider tunnelling across a p-n junction (a tunnelling diode) where the motion on both sides is constrained by quantum wells (QW) in the direction perpendicular to the interface to form 2D n-type and p-type electron gases. Coulomb interactions are neglected. The Hamiltonian near an intersection of the dispersion curves, E(k), of the n side and the p side resembles that of a relativistic Dirac electron. An electron, prepared in one of the QWs, will oscillate periodically between the two QWs with a frequency proportional to the tunnelling amplitude. In the tunnelling process, the velocity parallel to the interface is reversed resulting in periodic velocity oscillations similar to the Zitterbewegung where in the present case the opposite directions of the velocity are separated in space. We also find that the eigenstates have finite "persistent" circular currents which create magnetic moments of several Bohr magnetons, typically. The noise spectrum, and the linear response of the system are also obtained.
5 citations