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arXiv · 1211.4961

Nature of weak magnetism in SrTiO3/LaAlO3 multilayers

Z. Salman·O. Ofer·M. Radovic·H. Hao·K. H. Chow·M. D. Hossain·C. D. P. Levy·W. A. MacFarlane·G. M. Morris·L. Patthey·M. R. Pearson·H. Saadaoui·T. Schmitt·D. Wang·R. F. Kiefl
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Abstract

We report the observation of weak magnetism in superlattices of LaAlO3/SrTiO3 using beta-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 LaAlO3 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 LaAlO3/SrTiO3 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 (~0.002 muB) in the two samples with a larger LaAlO3 spacer thickness.

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Z. Salman, O. Ofer, M. Radovic, H. Hao, K. H. Chow, M. D. Hossain, C. D. P. Levy, W. A. MacFarlane, G. M. Morris, L. Patthey, M. R. Pearson, H. Saadaoui, T. Schmitt, D. Wang, R. F. Kiefl. 2012-11-21. Nature of weak magnetism in SrTiO3/LaAlO3 multilayers. https://doi.org/10.1103/physrevlett.109.257207

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