Injection Locking at Fractional Frequencies of Magnetic-Tunnel-Junction-Based Read Sensors’ Ferromagnetic Resonance Modes

As nanoscale magnetic devices such as sensors continue to shrink, in conjunction with being driven using higher current densities, the inherently nonlinear nature of magnetization dynamics may emerge during device operation. To optimize these nanodevices or choose the most favorable operating point, one needs a characterization protocol tailored to nonlinear measurements in the presence of dynamical effects. With this in mind, the authors develop such a protocol, which reveals a magnetic sensor's response at fractional frequencies of its natural ferromagnetic resonance modes. These resonances are then identified via micromagnetic modeling.