Spectral Analysis of Subterahertz Oscillations Based on an Antiferromagnet/Non–Magnetic Metal Heterostructure

We present a model of a sub-THz frequency spectrum analyzer based on the antiferromagnet/non–magnetic metal heterostructure. The considered structure operates in the active self–oscillation regime with the high Q–factor (closed to $10⁶$ ) and is phase–locked to the analyzed signal, while the frequency of the oscillator is linearly tuned by the spin–polarized current flowing through the non–magnetic metal. We find an analytical expression for the duration of the phase–locking interval by analyzing the generalized Kuramoto model with inertia. We show that the speed of the described spectrum analyzer is comparable to and exceeds the speed of modern commercial spectrum analyzers. The presented results can be helpful for practically realizing the room–temperature, tunable, sensitive, and high–speed sub-THz frequency spectrum analyzers.