Density-functional prediction of a surface magnetic phase in SrTiO(3)/LaAlO(3) heterostructures induced by Al vacancies.
Based on first-principles density functional calculations we propose a novel Al vacancy induced ferromagnetism occurring at the LaAlO(3) surface of SrTiO(3)/LaAlO(3) bilayers. Magnetism at cation vacancies away from the surface is quenched due to charge compensation. Magnetic surface Al vacancies are stabilized due to the built-in electric field inside the LaAlO(3) region that raises the energy of the defect level, making charge compensation unfavorable. Surface Al vacancies prefer to form clusters and exhibit two-dimensional ferromagnetic alignment mediated by a long-range magnetic interaction. These results are discussed in light of recent experimental observations.
School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia.
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Weston
Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales 2006, Australia and School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia.
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Cui
Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales 2006, Australia and School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia.
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Ringer
School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia.
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Stampfl