Viscous Spin Exchange Torque on Precessional Magnetization in(LaMnO3)2n/(SrMnO3)nSuperlattices

H. B. Zhao, K. J. Smith, Y. Fan, G. Lüpke, A. Bhattacharya, S. D. Bader, M. Warusawithana, X. Zhai, J. N. Eckstein
2008 Physical Review Letters  
Photoinduced magnetization dynamics is investigated in chemically ordered (LaMnO_3)_2n/(SrMnO_3)_n superlattices using the time-resolved magneto-optic Kerr effect. A monotonic frequency-field dependence is observed for the n=1 superlattice, indicating a single spin population consistent with a homogeneous hole distribution. In contrast, for n≥2 superlattices, a large precession frequency is observed at low fields indicating the presence of an exchange torque in the dynamic regime. We propose a
more » ... odel that ascribes the emergence of exchange torque to the coupling between two spin populations -- viscous and fast spins.
doi:10.1103/physrevlett.100.117208 pmid:18517824 fatcat:blniuxrzijee5baucivosjxsvy