A ferromagnet-normal-metal-ferromagnet trilayer does not conserve spin current and as a result, the conduction electrons can create a torque on the magnetic moments. When the trilayer is connected to a superconducting electrode, the spin torque created by a current flowing perpendicularly to the trilayer can drive the system to a configuration where the two magnetic moments are perpendicular to each other. Here we argue that in contrast to the non-equilibrium torque, the equilibrium torque (or magnetic exchange interaction) does not single out the perpendicular configuration. We calculate the equilibrium torque for a one-dimensional lattice model and find that it is sensitive to the presence of the superconductivity.
@article{arxiv.cond-mat/0107265,
title = {Spin torque in a magnetic trilayer coupled to a superconductor},
author = {Xavier Waintal and Piet W. Brouwer},
journal= {arXiv preprint arXiv:cond-mat/0107265},
year = {2007}
}
Comments
4 pages, 2 figures. To appear in the proceedings of the XXXVIth Rencontres de Moriond edited by T. Martin and G. Montambaux