Angular dependence of the electrically-driven and -detected ferromagnetic resonance

Electrically driven/detected ferromagnetic resonance (FMR) is a powerful technique for studying spin dynamics in magnetic materials and heterostructures. Here the magnetic moment of the specimen precesses about the direction of the static magnetic field and energy is absorbed strongly from the FMR-driving microwave current in the specimen when its frequency is equal to the precessional frequency. In this work we study the dependence of FMR on the relative orientation between the static magnetic field and the driving microwave current. The angular dependence of FMR in a Ni₃₄Fe₆₆ wire was measured for the magnetic field applied at an angle θ with respect to the wire and the driving current flowing along the wire. Both traditional microwave-absorption and electrical detection techniques show very similar behaviors with the resonance magnetic field following a simple “1/cos(θ)" dependence. Our findings emphasize the importance of the driving current direction in FMR experiments.