Nature of weak magnetism in SrTiO3/LaAlO3 multilayers

Z. Salman, O. Ofer, M. Radovic, H. Hao, M. Ben Shalom, K. H. Chow, Y. Dagan, 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

Research output: Contribution to journalArticlepeer-review

Abstract

We report the observation of weak magnetism in superlattices of LaAlO 3/SrTiO3 using β-detected nuclear magnetic resonance. The spin lattice relaxation rate of Li8 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 LaAlO 3/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 (∼0.002μB) in the two samples with a larger LaAlO3 spacer thickness.

Original languageEnglish
Article number257207
JournalPhysical Review Letters
Volume109
Issue number25
DOIs
StatePublished - 20 Dec 2012

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