Nature of weak magnetism in SrTiO3/LaAlO3 multilayers.
We report the observation of weak magnetism in superlattices of LaAlO(3)/SrTiO(3) using β-detected nuclear magnetic resonance. The spin lattice relaxation rate of ^{8}Li in superlattices with a spacer layers of 8 and 6 unit cells of LaAlO(3) exhibits a strong peak near ~35 K, whereas no such peak is observed in a superlattice with spacer layer thickness of 3 unit cells. We attribute the observed temperature dependence to slowing down of weakly coupled electronic moments at the LaAlO(3)/SrTiO(3) interface. These results show that the magnetism at the interface depends strongly on the thickness of the spacer layer, and that a minimal thickness of ~4-6 unit cells is required for the appearance of magnetism. A simple model is used to determine that the observed relaxation is due to small fluctuating moments (~0.002μ(B)) in the two samples with a larger LaAlO(3) spacer thickness.
Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland. zaher.salman@psi.ch
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Salman
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Ofer
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Radovic
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Hao
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Ben Shalom
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Chow
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Dagan
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Hossain
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Levy
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Macfarlane
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Morris
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Patthey
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Pearson
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Saadaoui
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Schmitt
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Wang
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Kiefl