Evidence for a current induced spin-transfer torque effect has been investigated in a series of point contacts to single ferromagnetic layers. At specific current densities, abrupt resistance changes, similar to those attributed to current-induced spin-wave excitations in multilayers, have been observed for one current polarity. The critical current for these resistance changes depends linearly on the external field applied perpendicular to the layer. The observed effect is interpreted as a current-driven heterogeneous instability in an otherwise uniform ferromagnetic layer.
Citation: Physical Review Letters
Pub Type: Journals
current-induced torque, magnetic instability, magnetic multilayers, point contact, spin current, spin waves, spin-transfer torque