Xi Chen, Qing-Rong Zheng, and Gang Su *
College of Physical Sciences, Graduate University of Chinese Academy of Sciences, P.O. Box 4588, Beijing 100049, China
(Received 31 May 2007; revised manuscript received 29 July 2007; published 8 October 2007)

Abstract:

     The possibility of oscillations of the tunnel conductance and magnetoresistance induced by spin wave excitations in a ferromagnet-ferromagnet-ferromagnet double-barrier tunnel junction, when the magnetizations of the two side ferromagnets are aligned antiparallel to that of the middle ferromagnet, is investigated in a self-consistent manner by means of Keldysh nonequilibrium Green’s function method. It has been found that owing to the s-d exchange interactions between conduction electrons and the spin density induced by spin accumulation in the middle ferromagnet, the differential conductance and the tunnel magnetoresistance indeed oscillate with the increase of bias voltage, being qualitatively consistent with the phenomenon that is observed recently in experiments. The effects of magnon modes, the energy levels of electrons, as well as the molecular field in the central ferromagnet on the oscillatory transport property of the system are also discussed.