Spin and orbital Ti magnetism at LaMnO3/SrTiO3 interfaces

• Published in: Nature communications Vol. 1; no. 1; p. 82
• Main Authors: Garcia-Barriocanal, J., Cezar, J.C., Bruno, F.Y., Thakur, P., Brookes, N.B., Utfeld, C., Rivera-Calzada, A., Giblin, S.R., Taylor, J.W., Duffy, J.A., Dugdale, S.B., Nakamura, T., Kodama, K., Leon, C., Okamoto, S., Santamaria, J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21-09-2010; Nature Publishing Group
• Subjects: 639/766/119; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms1080

In systems with strong electron-lattice coupling, such as manganites, orbital degeneracy is lifted, causing a null expectation value of the orbital magnetic moment. Magnetic structure is thus determined by spin–spin superexchange. In titanates, however, with much smaller Jahn–Teller distortions, orbital degeneracy might allow non-zero values of the orbital magnetic moment, and novel forms of ferromagnetic superexchange interaction unique to t
2g
electron systems have been theoretically predicted, although their experimental observation has remained elusive. In this paper, we report a new kind of Ti
3+
ferromagnetism at LaMnO
3
/SrTiO
3
epitaxial interfaces. It results from charge transfer to the empty conduction band of the titanate and has spin and orbital contributions evidencing the role of orbital degeneracy. The possibility of tuning magnetic alignment (ferromagnetic or antiferromagnetic) of Ti and Mn moments by structural parameters is demonstrated. This result will provide important clues for understanding the effects of orbital degeneracy in superexchange coupling.
The authors report a new kind of magnetism at the interface between two complex oxides, which shows both spin and orbital components due to degeneracy in the electronic states of SrTiO
3
. This could be useful in magnetic tunnel junctions and to further study superexchange coupling.