Emergent Phenomena in KTaO3/SrTiO3 Heterostructue

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 TiO0 2. By taking the epitaxial layers of SrTiO3 on top of KTaO3, we have created two different interfaces along (0 0 1), which are KO−/TiO0 2 and TaO+ 2/SrO0. We have studied these two interfaces by using density functional theory. In KO−/TiO0 2 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/SrO0 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