Magnetic and superconducting phases at the LaAlO₃/SrTiO₃ interface: The role of interfacial Ti 3d electrons

Authors

N. Pavlenko, Institute for Condensed Matter Physics
Thilo Kopp, Universitat AugsburgFollow
Evgeny Y. Tsymbal, University of Nebraska-LincolnFollow
George A. Sawatzky, University of British ColumbiaFollow
Jochen Mannhart, Max Planck Institute for Solid State ResearchFollow

Date of this Version

2012

Citation

PHYSICAL REVIEW B 85, (2012) 020407(R). DOI: 10.1103/PhysRevB.85.020407

Comments

Copyright © 2012 American Physical Society. Used by Permission.

Abstract

Ferromagnetism and superconductivity are, in most cases, adverse. However, recent experiments reveal that they coexist at interfaces of LaAlO₃ and SrTiO₃. We analyze the magnetic state within density functional theory and provide evidence that magnetism is not an intrinsic property of the two-dimensional electron liquid at the interface. We demonstrate that the robust ferromagnetic state is induced by the oxygen vacancies in SrTiO₃ or in the LaAlO₃ layer. This allows for the notion that areas with increased density of oxygen vacancies produce ferromagnetic puddles and account for the previous observation of a superparamagnetic behavior in the superconducting state.