Two‐Dimensional Electron Gases at the Amorphous and Crystalline SrTiO3/KTaO3 Heterointerfaces

Abstract

The 5d two‐dimensional electron gas (2DEG) based on KTaO3 (KTO) exhibits a lot of exotic properties such as stronger spin‐orbit coupling (SOC) and higher superconductivity transition temperature than those of SrTiO3 (STO)‐based 3d 2DEGs, whereas it has much lower electron mobility. Herein, the property of the 5d 2DEGs is investigated including the carrier mobility and Rashba SOC by interfacing both amorphous and crystalline STO with the crystalline KTO. Metallic 2DEGs are achieved at both interfaces of amorphous and crystalline STO‐capped KTO. Notably, the amorphous STO/KTO heterointerface has a larger carrier concentration and higher Hall mobility than the crystalline STO/KTO counterparts at low temperatures, which stems from two kinds of carriers. In contrast, the 5d 2DEG formed at the crystalline interface exhibits much stronger Rashba SOC as revealed through magnetotransport measurement. The deduced maximum strength of Rashba SOC and spin‐splitting energy are ≈8.56 × 10−12 eV m and ≈33.52 meV, respectively. Our results provide new insights on designing on‐demand properties of KTO‐based conducting interfaces.