Salman, Z.Ofer, O.Radovic, M.Hao, H.Ben Shalom, M.Chow, K. H.Dagan, Y.Hossain, M. D.Levy, C. D. P.Macfarlane, W. A.Morris, G. M.Patthey, L.Pearson, M. R.Saadaoui, H.Schmitt, T.Wang, D.Kiefl, R. F.2013-03-282013-03-282013-03-28201210.1103/PhysRevLett.109.257207https://infoscience.epfl.ch/handle/20.500.14299/91107WOS:000312841700013We report the observation of weak magnetism in superlattices of LaAlO3/SrTiO3 using beta-detected nuclear magnetic resonance. The spin lattice relaxation rate of Li-8 in superlattices with a spacer layers of 8 and 6 unit cells of LaAlO3 exhibits a strong peak near similar to 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 similar to 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 (similar to 0.002 mu(B)) in the two samples with a larger LaAlO3 spacer thickness. DOI: 10.1103/PhysRevLett.109.257207text::journal::journal article::research article