Surprising stability of polar (001) surfaces of the Mott insulator GdTiO3
Abstract
Using first-principles techniques based on hybrid density functional calculations, we study the stability, energetics, and electronic structure of the (001) surface of the Mott insulator GdTiO3 (GTO), which has an orthorhombic perovskite structure. Interestingly, we find the bare unreconstructed (but relaxed) polar surface terminated by a TiO2 plane to be very stable with a low surface energy (71 meV/Å2). As a test for stability of the TiO2 termination against reconstructions, we studied the influence of an H adatom. Hydrogen is known to form strong bonds with surface O atoms and passivate surface states, but contrary to expectations, hydrogen does not lead to a lowering of the GTO surface energy. We explain the energetics based on the surface electronic structure. We also address the interaction between the TiO2-terminated GTO surface and the high-density two-dimensional electron gas (2DEG) that can be formed at an SrTiO3 (STO)/GTO heterointerface. Unlike the situation in STO/LaAlO3 (LAO) heterostructures, where the LAO surface acts as a sink for electrons, the GTO surface does not drain electrons away from the 2DEG.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 01, 2021
- Source ID
- 10.1116/6.0001313
Entities
People
- Anderson Janotti
- Chris G. Van de Walle
- Karthik Krishnaswamy
- Lars Bjaalie
Organizations
- Defense Advanced Research Projects Agency
- National Science Foundation
- University of Delaware