Transient magnetic tunneling mediated by a molecular bridge

The archetypal molecular bridge – a single level molecular island connected by tunneling junctions to two massive leads – acquires new properties, if the leads are ferromagnetic metals. We have studied transient effects induced by suddenly connecting the leads in the parallel geometry. The tunneling is spin dependent and a local magnetization is formed on the level originally empty. The process depends on the strength U of the local electron-electron interaction and on the structure of the tunneling functions. A model prediction of the time evolution of the transient local magnetization is shown in the figure for reasonable values of U. The incipient coherent oscillations, almost independent on U, are damped. The saturation magnetization is first zero, for U increasing from zero, then negative, i.e. opposite with respect to the magnetization of the leads. At a critical value of U, the saturation magnetization reverts and further depends but weakly on increasing U. A.Kalvova,V.Spicka, B. Velicky J. Supercond. and Novel Magnetism 28 (2015) p. 1087-1091