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

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 t2g 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 t2g 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 t2g electron gas.

Epitaxial Oxides on Semiconductors: From Fundamentals to New Devices

“…Guo et al have also demonstrated growth of EuO on Si, in which a STO buffer was used to mediate epitaxy . Interestingly, the STO buffer layer also served as a source of oxygen during growth of the EuO film …”

Magnetic Conductive Outer Layer in Oxygen‐Deficient TiO2 Single Crystals

“…Furthermore, we can see an increase in MR with decreasing temperatures. At 10 K, the MR is about 40.5% at a high field of 10 T. More interestingly, the MR has a linear relation with the applied magnetic field at 10 K, while it has a roughly quadratic relation at T ≥ 20 K. We ascribe the origin of the positive linear MR to a Zeeman split of the electronic structure induced by magnetic ordering of oxygen vacancies, which is similar with the EuO/SrTiO 3 interface . The quadratic dependence of MR can be attributed to the ordinary Lorentz contribution which can increase the defect scattering from the enhanced transit path of electrons .…”

2D Electron Gas at the Interface of Atomic‐Layer‐Deposited Al2O3/TiO2 on SrTiO3 Single Crystal Substrate

“…The first‐suggested electronic reconstruction model, based on the charge mismatch (polar catastrophe) between the constituent cations, indicated that the 2DEG is localized at the topmost part of the STO substrate . There were several reports, however, that the nonpolar capping layer, such as amorphous LAO, yittria‐stabilized ZrO 2 , CaHfO 3 , amorphous Al 2 O 3 ( a ‐AO), and even ultrathin metal films, could feasibly produce the 2DEG on the similar STO substrate. These heterostructures are free from the charge mismatch effect, and as such, the electron accumulation at the interface cannot be induced by the suggested polar catastrophe effect.…”

“…ultrathin metal films, [13,14] could feasibly produce the 2DEG on the similar STO substrate. These heterostructures are free from the charge mismatch effect, and as such, the electron accumulation at the interface cannot be induced by the suggested polar catastrophe effect.…”