Electric-Field Control of Spin Current Generation and Detection in Ferromagnet-Free SrTiO₃-Based Nanodevices

Abstract

Spintronics entails the generation, transport, manipulation and detection of spin following the protocol outlined in the main text. Hall measurements give the change in subband population with respect to the gate voltage. Furthermore, the tight-binding band structure of the material allows us to compute the evolution of the charge filling with respect to the chemical potential. We use the Lifshitz transition as a reference point and assume that the population ratio of the heavy to the light sub-band is the same for both the experimental and numerical values. This yields a correspondence between the chemical potential and Vg and hence between and the sheet conductance .

Metal/ SrTiO3 two-dimensional electron gases for spin-to-charge conversion

“…First, for all three systems the measured voltage is large, corresponding to signals one to two orders of magnitude higher than what is typically found with, e.g., Pt or Ta. This is consistent with previous results in STO 2DEGs that showed remarkably high spin-charge conversion efficiencies [11,14,15,33,34]. The figure of merit (λ IEE ) of the spin-charge conversion efficiencies is defined as the ratio between the detected two-dimensional charge current and the injected three-dimensional spin current, and is expected to be proportional to the system's Rashba coefficient and the momentum relaxation time, i.e., λ IEE = α R τ /h.…”

Determining the Rashba parameter from the bilinear magnetoresistance response in a two-dimensional electron gas

“…We observe that α R increases from 2 meVÅ up to 50 meVÅ at V g = 120 V, where it reaches its maximum value. Beyond this, α R rapidly decreases, reaching a value of 20 meVÅ at V g = 150 V. This nonmonotonic behaviour is reminiscent of recent results in SrTiO 3 -based 2DEGs, where the spin-to-charge current conversion efficiency [37] and spin current generation and detection [32] were modulated up and down using gate voltages. The values extracted are in good agreement with the α R reported in other studies for the LAO/STO system in similar carrier density regimes [33,38].…”

Spin texture driven spintronic enhancement at the LaAlO$_3$/SrTiO$_3$ interface

“…In addition to displaying a significantly larger signal than in most materials where it is observed, the EE intensity changes with the electrostatic doping. Data analysis of nonlocal transport measurements also suggest that LAO/STO heterostructures host SHE [21].…”