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

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 alpha(R) that characterizes these systems. Here, we introduce a simple method that allows a quantitative extraction of alpha(R), 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 alpha(R) 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 alpha(R) in the region of the band structure where interband effects maximize the Rashba effect, consistent with theoretical predictions.