521 research outputs found
Weak antilocalization in a 2D electron gas with the chiral splitting of the spectrum
Motivated by the recent observation of the metal-insulator transition in
Si-MOSFETs we consider the quantum interference correction to the conductivity
in the presence of the Rashba spin splitting. For a small splitting, a
crossover from the localizing to antilocalizing regime is obtained. The
symplectic correction is revealed in the limit of a large separation between
the chiral branches. The relevance of the chiral splitting for the 2D electron
gas in Si-MOSFETs is discussed.Comment: 7 pages, REVTeX. Mistake corrected; in the limit of a large chiral
splitting the correction to the conductivity does not vanish but approaches
the symplectic valu
On the problem of catastrophic relaxation in superfluid 3-He-B
In this Letter we discussed the parametric instability of texture of
homogeneous (in time) spin precession, explaining how spatial inhomogeneity of
the texture may change the threshold of the instability in comparison with
idealized spatial homogeneous case, considered in our JETP Letter \textbf{83},
530 (2006), cond-mat/0605386. This discussion is inspired by critical Comment
of I.A. Fomin (cond-mat/0606760) related to the above questions. In addition we
considered here results of direct numerical simulations of the full
Leggett-Takagi equation of motion for magnetization in superfluid 3He-B and
experimental data for magnetic field dependence of the catastrophic relaxation,
that provide solid support of the theory of this phenomenon, presented in our
2006 JETP Letter.Comment: 5 pages, 1 fig. included, JETP Lett. style, submitted to JETP Lett.
as response to Comment cond-mat/060676
Solution of the problem of catastrophic relaxation of homogeneous spin precession in superfluid He-B
The quantitative analysis of the "catastrophic relaxation" of the coherent
spin precession in He-B is presented. This phenomenon has been observed
below the temperature about 0.5 T as an abrupt shortening of the induction
signal decay. It is explained in terms of the decay instability of homogeneous
transverse NMR mode into spin waves of the longitudinal NMR. Recently the cross
interaction amplitude between the two modes has been calculated by Sourovtsev
and Fomin \cite{SF} for the so-called Brinkman-Smith configuration, i.e. for
the orientation of the orbital momentum of Cooper pairs along the magnetic
field, . In their treatment, the interaction is
caused by the anisotropy of the speed of the spin waves. We found that in the
more general case of the non-parallel orientation of corresponding to
the typical conditions of experiment, the spin-orbital interaction provides the
additional interaction between the modes. By analyzing experimental data we are
able to distinguish which contribution is dominating in different regimes.Comment: 6 pages, 1 figure, submited to JETP letter
Zero-Field Satellites of a Zero-Bias Anomaly
Spin-orbit (SO) splitting, , of the electron Fermi surface
in two-dimensional systems manifests itself in the interaction-induced
corrections to the tunneling density of states, . Namely, in
the case of a smooth disorder, it gives rise to the satellites of a zero-bias
anomaly at energies . Zeeman splitting, , in a weak parallel magnetic field causes a narrow {\em plateau} of
a width at the top of each sharp satellite peak.
As exceeds , the SO satellites cross over to the
conventional narrow maxima at with SO-induced
plateaus at the tops.Comment: 7 pages including 2 figure
Berry phase and adiabaticity of a spin diffusing in a non-uniform magnetic field
An electron spin moving adiabatically in a strong, spatially non-uniform
magnetic field accumulates a geometric phase or Berry phase, which might be
observable as a conductance oscillation in a mesoscopic ring. Two contradicting
theories exist for how strong the magnetic field should be to ensure
adiabaticity if the motion is diffusive. To resolve this controversy, we study
the effect of a non-uniform magnetic field on the spin polarization and on the
weak-localization effect. The diffusion equation for the Cooperon is solved
exactly. Adiabaticity requires that the spin-precession time is short compared
to the elastic scattering time - it is not sufficient that it is short compared
to the diffusion time around the ring. This strong condition severely
complicates the experimental observation.Comment: 16 pages REVTEX, including 3 figure
Orbital mechanism of the circular photogalvanic effect in quantum wells
It is shown that the free-carrier (Drude) absorption of circularly polarized
radiation in quantum well structures leads to an electric current flow. The
photocurrent reverses its direction upon switching the light helicity. A pure
orbital mechanism of such a circular photogalvanic effect is proposed that is
based on interference of different pathways contributing to the light
absorption. Calculation shows that the magnitude of the helicity dependent
photocurrent in -doped quantum well structures corresponds to recent
experimental observations.Comment: 5 pages, 2 figures, to be published in JETP Letter
Hall-like effect induced by spin-orbit interaction
The effect of spin-orbit interaction on electron transport properties of a
cross-junction structure is studied. It is shown that it results in spin
polarization of left and right outgoing electron waves. Consequently, incoming
electron wave of a proper polarization induces voltage drop perpendicularly to
the direct current flow between source and drain of the considered
four-terminal cross-structure. The resulting Hall-like resistance is estimated
to be of the order of 10^-3 - 10^-2 h/e^2 for technologically available
structures. The effect becomes more pronounced in the vicinity of resonances
where Hall-like resistance changes its sign as function of the Fermi energy.Comment: 4 pages (RevTeX), 4 figures, will appear in Phys. Rev. Let
Non-Abelian Geometric Phases and Conductance of Spin-3/2 Holes
Angular momentum holes in semiconductor heterostructures are showed
to accumulate nonabelian geometric phases as a consequence of their motion. We
provide a general framework for analyzing such a system and compute conductance
oscillations for a simple ring geometry. We also analyze a figure-8 geometry
which captures intrinsically nonabelian interference effects.Comment: 4 pages, 3 figures (encapsulated PostScript) Replaced fig. 1 and fig.
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