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 EuTiO3 thin 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 to cm2V−1s−1 at 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+-3d states due to oxygen deficiency and the exchange interactions between interfacial Eu spins and itinerant Ti-3d electrons.
Surfaces and interfaces

Featured Article
High-mobility spin-polarized two-dimensional electron gas at the interface of EuTiO3/SrTiO3 heterostructures
Zhao-Cai Wang et al. 2021 J. Phys.: Condens. Matter 36 015001
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 EuTiO3 thin 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 to 5.5 x 103 cm2V−1s−1 at 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+-3d states due to oxygen deficiency and the exchange interactions between interfacial Eu spins and itinerant Ti-3d electrons.
Section scope
Papers in this section should report studies into the fundamental physics of surface, interface and atomic-scale systems. Topics covered in this section include the following:- Surfaces and interfaces: structural and electronic properties, dynamics, phonons
- 2D materials and layered systems: surface, interface and atomic-scale properties
- Growth, diffusion, and adsorbates on surfaces
- Surface phase transitions
- Atomic-scale science
- Thin films
- Tribology
Section editor

Steven Schofield University College London,UK
Steven Schofield is an Associate Professor in Condensed Matter Physics at University College London. He obtained his PhD in 2004 from the University of New South Wales, Australia. His research is focused on understanding and controlling the fundamental quantum properties of matter at the atomic scale using atomic-scale fabrication and cryogenic-temperature, ultrahigh-vacuum scanning tunnelling microscopy and spectroscopy, and complementary techniques such as photoemission and quantum simulation.