Spin Josephson effect in ferromagnet/ferromagnet tunnel junctionsF. S. Nogueira and K.-H. Bennemann
Institut für Theoretische Physik, Freie Universität Berlin Arnimallee 14, D-14195 Berlin, Germany
(Received 16 December 2003; accepted in final form 10 June 2004)
We consider the tunnel current between two ferromagnetic metals from a perspective similar to the one used in superconductor/superconductor tunnel junctions. We use fundamental arguments to derive a Josephson-like tunnel spin current . Here the phases are associated with the planar contribution to the magnetization, . The crucial step in our analysis is the fact that the z-component of the spin is canonically conjugate to the phase of the planar contribution: . This is the counterpart to the commutation relation in superconductors, where is the phase associated with the superconducting order parameter and N is the Cooper pair number operator. We briefly discuss the experimental consequences of our theoretical analysis.
72.25.-b - Spin polarized transport.
72.25.Mk - Spin transport through interfaces.
74.50.+r - Tunneling phenomena; point contacts, weak links, Josephson effects.
© EDP Sciences 2004