Field control of anisotropic spin transport and spin helix dynamics in a modulation-doped GaAs quantum well

Abstract

Electron spin transport and dynamics are investigated in a single, high-mobility, modulation-doped, GaAs quantum well using ultrafast two-color Kerr-rotation micro-spectroscopy, supported by qualitative kinetic theory simulations of spin diffusion and transport. Evolution of the spins is governed by the Dresselhaus bulk and Rashba structural inversion asymmetries, which manifest as an effective magnetic field that can be extracted directly from the experimental coherent spin precession. A spin precession length SOI is defined as one complete precession in the effective magnetic field. It is observed that application of (a) an out-ofplane electric field changes the spin decay time and SOI through the Rashba component of the spin-orbit coupling, (b) an in-plane magnetic field allows for extraction of the Dresselhaus and Rashba parameters, and (c) an in-plane electric field markedly modifies both the SOI and diffusion coefficient. While simulations reproduce the main features of the experiments, the latter results exceed the corresponding simulations and extend previous studies of drift-current-dependent spin-orbit interactions.

Persistent spin helix manipulation by optical doping of a CdTe quantum well

“…For the well width and 2DEG carrier density in our sample, it is estimated that 𝛽 1 ≈ 4.0𝛽 3 . Spin polarization of the photoexcited carriers evolves due to carrier diffusion in the presence of BSO, which can be directly measured using time-resolved polar magneto-optic Kerr microscopy [24,32]. Figure 1(a) shows the experimental scheme, wherein shaped pulses from a 60-MHz modelocked Ti:sapphire oscillator are used to photoexcite spin-polarized electrons in the conduction band at a photon energy above EF.…”

“…The experimental results are modeled within the framework of a kinetic equation for the complete spin distribution S described elsewhere [24,35] by Figure 3 (c) and (d) show results of kinetic-theory calculations [24,35] using input parameters determined from the experiment and including precession in the applied magnetic field with the electron 𝑔-factor (𝑔 = 1.8) determined independently. The calculations reproduce the stripe pattern observed in the experimental data, confirming the general spin dynamics [34].…”

“…Dual modulation-doping geometries lead to subbands either side of a soft barrier within the well [19,20] demonstrating a stretchable PSH by tuning  and  together [21]. Moderate in-plane electric fields will drive a spin helix to propagate [22], while the drift velocity can modify the PSH wavevector [23,24].…”

Управление долгоживущей спиновой спиралью / Пошакинский А.В., Paßmann F., Anghel S., Betz M., Тарасенко С.А.

“…А.Ф. Иоффе, 194021, Санкт-Петербург, Политехническая ул., 26 2 Технический университет Дортмунда, D-44227, Германия, Дортмунд, Otto-Hahn-Straße, 4a DOI 10.34077/Semicond2019-280 В полупроводниковых структурах с линейным по волновому вектору спин-орбитальным взаимодействием эволюция неоднородного спинового распределения электронов приводит к возникновению пространственных осцилляций спиновой плотности. Период такой спиновой спирали определяется наибольшей величиной спин-орбитального расщепления на поверхности Ферми, а ее направление -волновым вектором, для которого это расщепление реализуется [1].…”

“…Поворот внешнего поля в плоскости структуры приводит к переключению направления спиновой спирали. По углам наклона спиновых текстур для двух перпендикулярных направлений магнитного поля можно независимо определить константы спинорбитального взаимодействия Рашбы и Дрессельхауза [2]. При достаточно больших интенсивностях импульса накачки угол наклона спиновой текстуры оказывается непостоянным, см.…”