Low-Frequency Nonresonant Rectification in Spin Diodes

Spin diodes are usually resonant in nature (GHz frequency) and tunable by magnetic field and bias current with performances, in terms of sensitivity and minimum detectable power, overcoming the semiconductor counterpart, i.e., Schottky diodes. Recently, spin diodes characterized by a low-frequency detection (MHz frequency) have been proposed. Here, we show a strategy to design low-frequency detectors based on magnetic tunnel junctions with the interfacial perpendicular anisotropy of the same order of the demagnetizing field out-of-plane component. Micromagnetic calculations show that, to reach this detection regime, a threshold input power has to be overcome and the phase shift between the oscillation magnetoresistive signal and the input radiofrequency current plays a key role in determining the value of the rectification voltage.