Coupled-Mode Excitations Induced in an Antiferromagnetically Coupled Multilayer by Spin-Transfer Torque

摘要

Auto-oscillation of the magnetization in an Fe/Cr/Fe antiferromagnetically coupled multilayer was induced by spin-transfer torque. The acoustic mode, a coupled mode in the multilayer, was excited when a dc bias current was applied at relatively small magnetic fields. The external magnetic field dependence of the oscillation frequency is explained by a macrospin model with an antiferromagnetic coupling field. The excitation of the optical mode is also discussed.