Large positive linear magnetoresistance in the two-dimensional t 2g electron gas at the EuO/SrTiO3 interface

Kristy J Kormondy; Lingyuan Gao; Xiang Li; Sirong Lu; Agham B Posadas; Shida Shen; Maxim Tsoi; Martha R McCartney; David J Smith; Jianshi Zhou; Leonid L Lev; Marius-Adrian Husanu; Vladimir N Strocov; Alexander A Demkov

doi:10.1038/s41598-018-26017-z

Large positive linear magnetoresistance in the two-dimensional t _2g electron gas at the EuO/SrTiO₃ interface

Sci Rep. 2018 May 16;8(1):7721. doi: 10.1038/s41598-018-26017-z.

Authors

Kristy J Kormondy¹, Lingyuan Gao¹, Xiang Li², Sirong Lu³, Agham B Posadas¹, Shida Shen¹, Maxim Tsoi¹, Martha R McCartney⁴, David J Smith⁴, Jianshi Zhou², Leonid L Lev^{5

6}, Marius-Adrian Husanu^{5

7}, Vladimir N Strocov⁵, Alexander A Demkov⁸

Affiliations

¹ Department of Physics, The University of Texas at Austin, Austin, Texas, 78712, USA.
² Materials Science and Engineering Program/Mechanical Engineering, University of Texas at Austin, Austin, Texas, 78712, USA.
³ School of Engineering for Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, USA.
⁴ Department of Physics, Arizona State University, Tempe, Arizona, 85287, USA.
⁵ Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen PSI, Switzerland.
⁶ National Research Centre "Kurchatov Institute", 1 Akademika Kurchatova pl., 123182, Moscow, Russia.
⁷ National Institute of Materials Physics, 405A Atomistilor Str., 077125, Magurele, Romania.
⁸ Department of Physics, The University of Texas at Austin, Austin, Texas, 78712, USA. demkov@physics.utexas.edu.

Abstract

The development of novel nano-oxide spintronic devices would benefit greatly from interfacing with emergent phenomena at oxide interfaces. In this paper, we integrate highly spin-split ferromagnetic semiconductor EuO onto perovskite SrTiO₃ (001). A careful deposition of Eu metal by molecular beam epitaxy results in EuO growth via oxygen out-diffusion from SrTiO₃. This in turn leaves behind a highly conductive interfacial layer through generation of oxygen vacancies. Below the Curie temperature of 70 K of EuO, this spin-polarized two-dimensional t _2g electron gas at the EuO/SrTiO₃ interface displays very large positive linear magnetoresistance (MR). Soft x-ray angle-resolved photoemission spectroscopy (SX-ARPES) reveals the t _2g nature of the carriers. First principles calculations strongly suggest that Zeeman splitting, caused by proximity magnetism and oxygen vacancies in SrTiO₃, is responsible for the MR. This system offers an as-yet-unexplored route to pursue proximity-induced effects in the oxide two-dimensional t _2g electron gas.