The emergence of magnetic ordering at complex oxide interfaces tuned by defects

Abstract

Complex oxides show extreme sensitivity to structural distortions and defects, and the intricate balance of competing interactions which emerge at atomically defined interfaces may give rise to unexpected physics. In the interfaces of non-magnetic complex oxides, one of the most intriguing properties is the emergence of magnetism which is sensitive to chemical defects. Particularly, it is unclear which defects are responsible for the emergent magnetic interfaces. Here, we show direct and clear experimental evidence, supported by theoretical explanation, that the B-site cation stoichiometry is crucial for the creation and control of magnetism at the interface between non-magnetic ABO 3-perovskite oxides, LaAlO 3 and SrTiO 3. We find that consecutive defect formation, driven by atomic charge compensation, establishes the formation of robust perpendicular magnetic moments at the interface. Our observations propose a route to tune these emerging magnetoelectric structures, which are strongly coupled at the polar-nonpolar complex oxide interfaces.

Large Linear Magnetoresistance of High‐Mobility 2D Electron System at Nonisostructural γ‐Al2O3/SrTiO3 Heterointerfaces

“…The 2D electron system (2DES) formed at the complex oxide heterointerfaces provides a marvelous variety of emergent physical phenomena and novel functionalities, such as high carrier mobility, [ 1,2 ] magnetism, [ 3 ] superconductivity, [ 4 ] quantum transport, [ 5 ] Rashba spin–orbit coupling (SOC), [ 6 ] high‐efficient spin‐charge conversion, [ 7–9 ] and effective tunability via external multistimuli. [ 10,11 ] Among these heterointerfaces, the benchmark LaAlO 3 /SrTiO 3 (LAO/STO) interface with isostructural perovskite structure is mostly studied to date.…”

On the resistance minimum in LaAlO$_3$/Eu$_{1-x}$La$_x$TiO$_3$/SrTiO$_3$ heterostructures

“…With introducing Eu doping, we observe an increase of the AHE magnitude contrary to Ref. cation defects in the LAO layer 9 . Indeed we observe in our samples the presence of Ti deeper in the LAO layer, which can give an additional contribution to the magnetism.…”

“…One outstanding feature, of interest for spintronics applications, is the tunability of the spin polarisation or magnetism. Its signature, the Anomalous Hall effect (AHE), was extensively studied in the past decade in various STO-based structures [1][2][3][4][5][6][7][8][9] . It was shown, in particular, that the AHE can be completely switched off by a gate voltage, at least in some of this structures.…”

Intrinsic versus extrinsic orbital and electronic reconstructions at complex oxide interfaces

“…2,3 Orbital, spin, and electronic reconstructions which can occur at the atomically precise interfaces lead to emergent properties that are often very different from the corresponding bulk materials. 3 The interface between LaAlO 3 and SrTiO 3 (LAO/STO) is paradigmatic of the oxide heterostructure field, hosting a two dimensional electron liquid (2DEL) 4,5 that exhibits gate-tunable superconductivity, [6][7][8][9][10][11] flexoelectricity, 12 magnetism, [13][14][15] and correlations. 16,17 Recent experiments have further utilized this interface as a foundation for the construction of one-dimensional superconducting electron waveguides 7,18,19 which have potential application in quantum computing.…”