Search

We evaluate the spin polarization (Edelstein or inverse spin galvanic effect) and the spin Hall current induced by an applied electric field by including the weak localization corrections for a two-dimensional electron gas. We show that the weak localization effects yield logarithmic corrections to both the spin polarization conductivity relating the spin polarization and the electric field and to the spin Hall angle relating the spin and charge currents. The renormalization of both the spin polarization conductivity and the spin Hall angle combine to produce a zero correction to the total spin Hall conductivity as required by an exact identity. Suggestions for the experimental observation of the effect are given. [ABSTRACT FROM AUTHOR]

We have performed conductivity measurements on a Si-MOSFET sample with a slot in the upper gate, allowing for different electron densities n1 and n2 across the slot. Dynamic longitudinal resistance was measured by a standard lock-in technique, while maintaining a large dc current through the source-drain channel. We find that in a parallel magnetic field, the resistance of the sample R(Idc) is asymmetric with respect to the direction of the dc current. The asymmetry becomes stronger with an increase of either the magnetic field or the difference between n1 and n2. These observations are interpreted in terms of the effective spin injection: the degree of spin polarization is different in the two parts of the sample, implying different magnitudes of spin current away from the slot. The carriers thus leave the excess spin (of the appropriate sign) in the region around the slot, leading to spin accumulation (or depletion) and to the spin-drift-diffusion phenomena. Due to the positive magnetoresistance of the two-dimensional electron gas, this change in a local magnetization affects the resistivity near the slot and the measured net resistance, giving rise to an asymmetric contribution. We further observe that the value of R(Idc) saturates at large Idc; we suggest that this is due to electron tunneling from the two-dimensional n-type layer into the p-type silicon (or into another "spin reservoir") at the slot. [ABSTRACT FROM AUTHOR]

The spin-dependent electron transport is theoretically investigated in a two-dimensional electron gas, which is periodically modulated by ferromagnetic and Schottky metal (SM) stripes. We find that the spin-dependent transmission and conductance as well as polarization strongly depend on the number of periods. We also find that the transmission and the polarization of transmitted beams periodically change with increasing the width of the SM stripe. [ABSTRACT FROM AUTHOR]

Abstract: We present a theoretical study on the spin-dependent electron transport in a two-dimensional electron gas (2DEG) modulated by a stripe of magnetized ferromagnetic metal under an applied voltage. It is shown that highly spin-polarized current can be achieved in this kind of nanosystems. It is also shown that the spin polarity of the electron transport can be switched by adjusting the applied voltage to the stripe in the device. These interesting properties may provide an alternative scheme to spin-polarize electrons into semiconductors, and this device may be used as a voltage-tunable spin-filter. [Copyright &y& Elsevier]