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

Abstract

Two-dimensional (2D) Rashba systems have been intensively studied in the last decade due to their unconventional physics, tunability capabilities, and potential for spin-charge interconversion when compared to conventional heavy metals. With the advent of a new generation of spin-based logic and memory devices, the search for Rashba systems with more robust and larger conversion efficiencies is expanding. Conventionally, demanding techniques such as angle-and spin-resolved photoemission spectroscopy are required to determine the Rashba parameter αR that characterizes these systems. Here, we introduce a simple method that allows a quantitative extraction of αR, through the analysis of the bilinear response of angle-dependent magnetotransport experiments. This method is based on the modulation of the Rashba-split bands under a rotating in-plane magnetic field. We show that our method is able to correctly yield the value of αR for a wide range of Fermi energies in the 2D electron gas at the LaAlO3/SrTiO3 interface. By applying a gate voltage, we observe a maximum αR in the region of the band structure where interband effects maximize the Rashba effect, consistently with theoretical predictions.

Spin–Charge Interconversion in KTaO3 2D Electron Gases

“…and Vaz et al. measured a unidirectional magnetoresistance (coined the bilinear magnetoresistance) in an LAO//STO 2DEG, [ 15,16 ] caused by the DEE, which generates a spin density transverse to the applied charge current that changes sign when the current is reversed (see Figure 1c,d).…”

From low-field Sondheimer oscillations to high-field very large and linear magnetoresistance in a SrTiO$_3$-based two-dimensional electron gas

“…Further, samples with high mobilities exhibit Shubnikov-de Haas oscillations 4,5 and quantum Hall effect. 6 A peculiar angular dependence of the resistance, including a unidirectional magnetoresistance 7,8 and high order oscillations, 9 has also been reported. 8,[10][11][12] A few studies also mention a linear magnetoresistance (MR) for perpendicular magnetic field B 13,14 with, in some cases, a very large amplitude (>500% at 9 T).…”

“…6 A peculiar angular dependence of the resistance, including a unidirectional magnetoresistance 7,8 and high order oscillations, 9 has also been reported. 8,[10][11][12] A few studies also mention a linear magnetoresistance (MR) for perpendicular magnetic field B 13,14 with, in some cases, a very large amplitude (>500% at 9 T). 13 This is reminiscent of a giant, non-saturating linear MR reported in various systems including narrow bandgap semiconductors, 15 graphene, 16,17 semimetals, [18][19][20] and topological insulators.…”

Spin to charge conversion at Rashba-split SrTiO$_3$ interfaces from resonant tunneling

“…The interconversion between spin and charge currents mediated by Rashba interactions 1 , observed in a wide range of systems (Ag/Bi interfaces 2 , SrTiO 3 two-dimensional electron gases (STO 2DEGs) [3][4][5][6][7][8] CoFeB/MgO 9 , Fe/Ge, α-Sn 2,10 ), offers huge technological opportunities from spin orbit torque and magnetic commutation to THz wave generation [11][12][13][14][15] . In Rashba systems, a flow of charge results in an out-of equilibrium spin density arising from the uncompensated spin-texture at the Fermi surfaces, the so-called Rashba-Edelstein effect (REE) [16][17][18] .…”