Room‐Temperature Charge‐to‐Spin Conversion from Quasi‐2D Electron Gas at SrTiO₃‐Based Interfaces

Abstract

Interfacial two‐dimensional electron gases (2DEG), especially the SrTiO 3 ‐based ones at the unexpected interface of insulators, have emerged to be promising candidates for efficient charge–spin interconversion. Herein, to gain insight into the mechanism of the charge–spin interconversion, quasi‐2DEG between insulating SrTiO 3 and two types of aluminum‐based amorphous insulators, namely SrTiO 3 /AlN and SrTiO 3 /Al 2 O 3 , are focused on and their charge‐to‐spin conversion efficiency is estimated. The two types of amorphous insulators are selected to probe the overlooked contribution of oxygen vacancy. A mechanism to explain the results of spin–torque ferromagnetic resonance measurements is proposed and an analysis protocol to reliably estimate in quasi‐2DEG is developed. The resultant, thickness of the 2DEG, is estimated to be 0.244 and 0.101 nm −1 for SrTiO 3 /AlN and SrTiO 3 /Al 2 O 3 , respectively, which are strikingly comparable to their crystalline counterparts. Furthermore, a large direct current modulation of resonance linewidth in SrTiO 3 /AlN samples is developed, confirming and attesting an oxygen vacancy‐enabled charge–spin conversion. The findings emphasize the defects' contribution‐, especially in oxide‐based low‐dimensional systems, and provide a way to create and enhance charge–spin interconversion via defect engineering.