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arXiv · 0706.2157

Viscous spin exchange torque on precessional magnetization in $(\mathrm{LaMnO}_3)_{2n}/(\mathrm{SrMnO}_3)_{n}$ superlattices

H. B. Zhao·K. J. Smith·Y. Fan·G. Lüpke·A. Bhattacharya·S. D. Bader·M. Warusawithana·X. Zhai·J. N. Eckstein
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Abstract

Photoinduced magnetization dynamics is investigated in chemically ordered $(\mathrm{LaMnO}_3)_{2n}/(\mathrm{SrMnO}_3)_n$ 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 $n\geq2$ superlattices, a large precession frequency is observed at low fields indicating the presence of an exchange torque in the dynamic regime. We propose a model that ascribes the emergence of exchange torque to the coupling between two spin populations -- viscous and fast spins.

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H. B. Zhao, K. J. Smith, Y. Fan, G. Lüpke, A. Bhattacharya, S. D. Bader, M. Warusawithana, X. Zhai, J. N. Eckstein. 2007-06-14. Viscous spin exchange torque on precessional magnetization in $(\mathrm{LaMnO}_3)_{2n}/(\mathrm{SrMnO}_3)_{n}$ superlattices. https://doi.org/10.1103/physrevlett.100.117208

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