Drift transport of helical spin coherence with tailored spin–orbit interactions

Abstract

Most future information processing techniques using electron spins in non-magnetic semiconductors will require both the manipulation and transfer of spins without their coherence being lost. The spin–orbit effective magnetic field induced by drifting electrons enables us to rotate the electron spins in the absence of an external magnetic field. However, the fluctuations in the effective magnetic field originating from the random scattering of electrons also cause undesirable spin decoherence, which limits the length scale of the spin transport. Here we demonstrate the drift transport of electron spins adjusted to a robust spin structure, namely a persistent spin helix. We find that the persistent spin helix enhances the spatial coherence of drifting spins, resulting in maximized spin decay length near the persistent spin helix condition. Within the enhanced distance of the spin transport, the transport path of electron spins can be modulated by employing time-varying in-plane voltages.

Emergence of the giant out-of-plane Rashba effect and tunable nanoscale persistent spin helix in ferroelectric SnTe thin films

“…The channel length would be set to l PSH /4 (modulo l PSH /2), corresponding to π/2 (modulo π) spin precession of the PSH. Injection of the spin-polarized electron from the source electrode into the SnTe channel would rotate the traversing spin around the z-axis by π/2 (modulo π) at the end of the channel [24]. Because the spin configurations of the ferromagnetic source and drain electrodes would be orthogonal, the electron spin at the end of the SnTe channel would be either parallel or antiparallel to the spin orientation of the drain, leading to an on-or offstate, respectively.…”

Spin accumulation in photo-induced potential dimples generated in semiconductors

“…This fact enabled us to enhance the electron spin lifetime in the QW by reducing the spatial size of the photo-induced confinement. This temporal and reformable way of modulating potential profiles for spins in semiconductors offers a solution to extend the spin lifetime in a different approach from those reported previously [5][6][7][8][9][10][11][12][13][14][15][16][17][18][20][21][22][23][24][25][26][27] , and opens the way to the efficient control of spin coherence in future spintronics applications.…”

“…Unfortunately, the SOI also has an adverse effect on the spin coherence lifetime, which is shortened by the fluctuating spin-orbit magnetic fields associated with the random motion of the diffusive two-dimensional electrons 2 . The tunability of SOI provides a solution; a balanced Rashba 3 and Dresselhaus 4 SOI condition for two-dimensional electron gas (2DEG) in zinc-blende type semiconductors provides an SU(2) spin-rotation symmetry, and the resultant persistent spin helix mode can have an extended lifetime [5][6][7][8] . Another approach, which does not require the precise tuning of the Rashba SOI, is to reduce the confinement size; the spin relaxation mechanism can be suppressed by confining electrons spins further towards a one [9][10][11][12][13][14] or zero [15][16][17][18] dimensional area.…”

Deterministic transfer of spin polarization in wire-like lateral structures via the persistent spin helix

“…15 Very recently, investigations in biased structures under charge transport were reported. 16,17 In this work, we used spatially-and time-resolved Kerr rotation microscopy to show that spin polarization can be deterministically transferred to specific lateral positions via the PSH. We started by experimentally verifying the PSH in the as-grown sample, a GaAs-AlGaAs single quantum well, via spatially-resolved Kerr microscopy, followed by the investigation of narrow channels with lateral widths down to 3 lm.…”