Aharonov-Casher and spin Hall effects in mesoscopic ring structures with strong spin-orbit interaction

Abstract

We study the quantum interference effects induced by the Aharonov-Casher phase in asymmetrically confined two-dimensional electron and heavy-hole ring structure systems, taking into account the electrically tunable spin-orbit ͑SO͒ interaction. We have calculated the nonadiabatic transport properties of charges ͑heavy holes and electrons͒ in two-probe thin-ring structures and compare how the form of the SO coupling of the carriers affects it. We show that both the SO splitting of the bands and the carrier density can be used to modulate the conductance through the ring. We show that the dependence on carrier density is due to the backscattering from the leads, which shows pronounce resonances when the Fermi energy is close to the eigenenergy of the ring. We also calculate the spin Hall conductivity and longitudinal conductivity in fourprobe rings as a function of the carrier density and SO interaction, demonstrating that for heavy-hole carriers both conductivities are larger than for electrons. Finally, we investigate the transport properties of mesoscopic rings with spatially inhomogeneous SO coupling. We show that devices with inhomogeneous SO interaction exhibit an electrically controlled spin-flipping mechanism.

Spin-charge conversion in a multiterminal Aharonov-Casher ring coupled to precessing ferromagnets: A charge-conserving Floquet nonequilibrium Green function approach

“…(34) and (35), we show and examine our numerical results for two-and four-terminal spin-pumping setups with the parameters and units specified in Sec. IV A.…”

“…(32), (33), (34), and (35), we solve the Floquet-NEGF equations and use the so-called reduced-zone scheme 35 which guarantees conservation of charge currents for any given maximum number of photons, unlike other recent approaches based on continued-fraction solutions [37][38][39][40] where charge conservation is ensured only in the limit of infinite number of photons. (ii) With Fig.…”

Anomalous spin-related quantum phase in mesoscopic hole rings

“…The HH model predicts ⌬V SIA = V 41 / ͑n F 2 d R ͒ 1/2 for a ring with n F occupied 1D subbands. 24,25 Interestingly, the experiment reported in Ref. 15 observed an order-of-magnitude discrepancy between the measured value and that expected from application of the HH model.…”

“…Section IV focuses on the spin-related Aharonov-Anandan phase and how it is revealed in magnetoconductance oscillations. The frequently used [24][25][26] heavy-hole model for p-type mesoscopic rings is introduced in Sec. V and results obtained using it are compared with those found within our more complete theory.…”

“…Recent calculations [24][25][26] of the magnetoconductance in hole rings adopted a purely heavy-hole ͑HH͒ model where only the valence-band states with spin projection Ϯ3 / 2 ͑heavy holes͒ and their effective Rashba-type spin splitting are taken into account. It is tempting to follow such a route because the highest quasi-two-dimensional ͑2D͒ valence subband is mostly of HH character for typical hole sheet densities, 17 and the HH model bears resemblance to the one that applies to conduction-band electrons.…”