Intrinsic magnetism in KTaO${}_3$ heterostructures

Abstract

There has been intense recent interest in the two-dimensional electron gases (2DEGs) that form at the surfaces and interfaces of KTaO${}_3$ (KTO), with the discovery of superconductivity at temperatures significantly higher than those of similar 2DEGs based on SrTiO${}_3$ (STO). Like STO heterostructures, these KTO 2DEGs are formed by depositing an overlayer on top of appropriately prepared KTO surfaces. Some of these overlayers are magnetic, and the resulting 2DEGs show signatures of this magnetism, including hysteresis in the magnetoresistance (MR). Here we show that KTO 2DEGs fabricated by depositing AlO${}_x$ on top of KTO also show hysteretic MR, indicative of long range magnetic order, even though the samples nominally contain no intrinsic magnetic elements. The hysteresis appears in both the transverse and longitudinal resistance in magnetic fields both perpendicular to and in the plane of the 2DEG. The hysteretic MR has different characteristic fields and shapes for surfaces of different crystal orientations, and vanishes above a few Kelvin. Density functional theory (DFT) calculations indicate that the magnetism likely arises from Ta${}^{4+}$ local moments created in the presence of oxygen vacancies.

5 pages, 4 figures, supplemental materials. arXiv admin note: text overlap with arXiv:2209.10534

References in corpus (4)

• Magnetic effects at the interface between nonmagnetic oxides
• Highly efficient and tuneable spin-to-charge conversion through Rashba coupling at oxide interfaces
• Observation of Inverse Edelstein Effect in Rashba-Split 2DEG between SrTiO3 and LaAlO3 at Room Temperature
• Evidence for charge-vortex duality at the LaAlO${}_3$/SrTiO${}_3$ interface

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