High-mobility spin-polarized two-dimensional electron gas at the interface of EuTiO3/SrTiO3heterostructures

Zhao-Cai Wang; Ying Zhang; Zheng-Nan Li; Shuang-Shuang Li; Jing-Shi Ying; Wei Yan; Lei Chen; Shu-Juan Zhang; Fu-Sheng Luo; Weiyao Zhao; Mao Ye; Ren-Kui Zheng

doi:10.1088/1361-648X/acfc90

High-mobility spin-polarized two-dimensional electron gas at the interface of EuTiO₃/SrTiO₃heterostructures

J Phys Condens Matter. 2023 Oct 3;36(1). doi: 10.1088/1361-648X/acfc90.

Authors

Zhao-Cai Wang¹, Ying Zhang¹, Zheng-Nan Li¹, Shuang-Shuang Li¹, Jing-Shi Ying¹, Wei Yan¹, Lei Chen², Shu-Juan Zhang³, Fu-Sheng Luo⁴, Weiyao Zhao⁵, Mao Ye², Ren-Kui Zheng^{1

2}

Affiliations

¹ School of Physics and Materials Science and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, People's Republic of China.
² School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, People's Republic of China.
³ School of Materials and Mechanic & Electrical Engineering, Jiangxi Science and Technology Normal University, Nanchang 330038, People's Republic of China.
⁴ School of Physics and Electronic Information, Gannan Normal University, Ganzhou 341000, People's Republic of China.
⁵ Department of Materials Science & Engineering, Monash University, Clayton VIC 3800, Australia.

PMID: 37738991
DOI: 10.1088/1361-648X/acfc90

Abstract

Spin polarization of two-dimensional electron gas (2DEG) at the interface of EuTiO₃/SrTiO₃(STO) heterostructures has been theoretical predicted and experimentally observed via x-ray magnetic circular dichroism and polarized x-ray absorption spectroscopy, which, however, is lack of magnetotransport evidence. Here, we report the fabrication of high-quality EuTiO₃/STO heterostructures by depositing antiferromagnetic insulating EuTiO₃thin films onto STO substrates. Shubnikov-de Haas oscillation, Hall, and magnetoresistance (MR) measurements show that the interface is not only highly conducting, with electron mobility up to5.5×103cm²V^-1s^-1at 1.8 K, but also shows low-field hysteretic MR effects. MR of ∼9% is observed at 1.8 K and 20 Oe, which is one order of magnitude higher than those observed in other spin-polarized 2DEG oxide systems. Moreover, the heterostructures show ferromagnetic hysteresis loops. These results demonstrate that the high-mobility 2DEG is spin polarized, whose origin is attributed to the interfacial Ti³⁺-3dstates due to oxygen deficiency and the exchange interactions between interfacial Eu spins and itinerant Ti-3delectrons.

Keywords: Shubnikov-de Haas oscillation; interface; low-field hysteretic MR; spin polarized 2DEG.