Ferromagnetic exchange, spin–orbit coupling and spiral magnetism at the LaAlO3/SrTiO3 interface

The interface between two non-magnetic band insulators, LaAlO 3 and SrTiO 3 , can exhibit conductivity, superconductivity and magnetism. These interfacial phenomena can be reconciled by a theory that predicts a spiral magnetic ground state. The electronic properties of the polar interface between in...

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Veröffentlicht in:Nature physics Jg. 9; H. 10; S. 626 - 630
Hauptverfasser: Banerjee, Sumilan, Erten, Onur, Randeria, Mohit
Format: Journal Article
Sprache:Englisch
Veröffentlicht: London Nature Publishing Group UK 01.10.2013
Nature Publishing Group
Schlagworte:
639/301/119/995
Atomic
Classical and Continuum Physics
Complex Systems
Condensed Matter Physics
Conduction electrons
Electron spin
Electronic properties
Electrons
Ferromagnetism
Ground state
Insulators
letter
Magnetic materials
Magnetic measurement
Magnetic properties
Magnetism
Mathematical and Computational Physics
Molecular
Optical and Plasma Physics
Physics
Spin-orbit interactions
Strontium titanates
Superconducting quantum interference devices
Superconductivity
Theoretical
ISSN:1745-2473, 1745-2481
Online-Zugang:Volltext
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Zusammenfassung:The interface between two non-magnetic band insulators, LaAlO 3 and SrTiO 3 , can exhibit conductivity, superconductivity and magnetism. These interfacial phenomena can be reconciled by a theory that predicts a spiral magnetic ground state. The electronic properties of the polar interface between insulating oxides is a subject of great interest 1 , 2 , 3 . An exciting development is the observation of robust magnetism 4 , 5 , 6 , 7 , 8 at the interface of two non-magnetic materials, LaAlO 3 (LAO) and SrTiO 3 (STO). Here we present a microscopic theory for the formation and interaction of local moments that depends on essential features of the LAO/STO interface. We show that correlation-induced moments arise owing to interfacial splitting of orbital degeneracy. We find that conduction electrons with a gate-tunable Rashba spin–orbit coupling mediate ferromagnetic exchange with a twist. We predict that the zero-field ground state is a long-wavelength spiral. Its evolution in an external field accounts semi-quantitatively for torque magnetometry data 5 and describes qualitative aspects of the scanning superconducting quantum interference device measurements 6 . We make several testable predictions for future experiments.
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ISSN:1745-2473
1745-2481
DOI:10.1038/nphys2702