Emergent Phenomena in KTaO₃/SrTiO₃ Heterostructure

Abstract

KTaO3 has become a new material of attraction for exploring various exotic properties at its surface and interfaces. To explore the substrate effect of KTaO3, we have studied a new heterostructure made by KTaO3 and SrTiO3. KTaO3 is a 5d polar perovskite with the complementary planes of KO− and TaO 2 + , whereas SrTiO3 is a 3d non-polar perovskite with alternative stacking SrO0 and TiO 2 0 . By taking the epitaxial layers of SrTiO3 on top of KTaO3, we have created two different interfaces along (0 0 1), which are KO − / TiO 2 0 and TaO 2 + / SrO 0 . We have studied these two interfaces by using density functional theory. In KO − / TiO 2 0 interface, the signature of two-dimensional hole gas (2DHG) has been found. Though the interface turns to insulator when epitaxial layers reach beyond 4.5 u.c. The other one, i.e., TaO 2 + / SrO 0 interface, shows the typical behaviour of two-dimensional electron gas (2DEG), only at the epitaxial layer 2.5 uc. The presence of both types of carriers in a single system for different kinds of interfaces has great use in various device applications.