期刊
THIN SOLID FILMS
卷 583, 期 -, 页码 129-134出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.tsf.2015.03.065
关键词
Molecular beam epitaxy; Oxygen stability; Metal-insulator transition; Small polaron; Fermi liquid
类别
资金
- MURI program of the Army Research Office [W911-NF-09-1-0398]
- U.S. National Science Foundation [DMR-1006640]
- DOE [DE-SC0001009]
- Department of Defense
- Direct For Mathematical & Physical Scien [1006640] Funding Source: National Science Foundation
- Division Of Materials Research [1006640] Funding Source: National Science Foundation
Growth of epitaxial Gd-1 - xSrxTiO3 thin films using hybrid molecular beam epitaxy and stability of thin films in oxygen rich atmospheres at elevated temperatures are investigated. Only Sr-rich films with x > 0.95 were stable at such conditions. GdTiO3 is a ferrimagnetic Mott insulator while SrTiO3 is a diamagnetic band insulator. The metal-insulator transition occurs by electron doping of SrTiO3 (Gd-doped SrTiO3) or hole doping of GdTiO3 (Sr-doped GdTiO3). The latter is investigated in more detail. It is shown that the insulating state, even in undoped GdTiO3, is dominated by small polaron hopping, which transitions to metallic, Fermi-liquid-type conduction with large amounts of Sr alloying. The metal-insulator transition is also accompanied by transition from n-type to p-type conduction. Furthermore, ferrimagnetismpersists into the metallic phase. The results show that the insulating phase is stabilized even for large amounts of Sr doping by polaron formation, and that the transition to the metallic phase occurs via a continuous first order transition and a two phase region. (C) 2015 Elsevier B.V. All rights reserved.
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