Surprising stability of polar (001) surfaces of the Mott insulator GdTiO3

Autor:	Karthik Krishnaswamy, Anderson Janotti, Chris G. Van de Walle, Lars Bjaalie
Rok vydání:	2021
Předmět:	Materials science Condensed matter physics Hydrogen Mott insulator chemistry.chemical_element Heterojunction Surfaces and Interfaces Electronic structure Electron Condensed Matter Physics Surface energy Surfaces Coatings and Films chemistry Fermi gas Surface states
Zdroj:	Journal of Vacuum Science & Technology A. 39:063220
ISSN:	1520-8559 0734-2101
Popis:	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 GdTiO 3 (GTO), which has an orthorhombic perovskite structure. Interestingly, we find the bare unreconstructed (but relaxed) polar surface terminated by a TiO 2 plane to be very stable with a low surface energy (71 meV/A 2). As a test for stability of the TiO 2 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 TiO 2-terminated GTO surface and the high-density two-dimensional electron gas (2DEG) that can be formed at an SrTiO 3 (STO)/GTO heterointerface. Unlike the situation in STO/LaAlO 3 (LAO) heterostructures, where the LAO surface acts as a sink for electrons, the GTO surface does not drain electrons away from the 2DEG.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::25b9aedaa8176a02ffe3594ed23f45cc https://doi.org/10.1116/6.0001313 Zobrazit plný text záznamu