Current tunable barium hexaferrite millimeter wave resonator

This report is on non‐linear magneto‐electric (ME) interactions due to an electric current in single crystal M‐type barium hexaferrite (BaM). The interaction results in variations in the magnetic order parameters and manifests as tuning of magnetic modes in a BaM resonator in the U‐band. A DC current along the c‐axis of the ferrite is found to tune the frequency of the magnetic mode by 400 MHz when the sample is in the single‐domain state and by 70 MHz in the multi‐domain state for currents up to 20 mA and applied voltages up to 75 V. The current tuning of the frequency is found to be linear with electric power for both single‐domain and multi‐domain resonances. The shift in mode frequency due to current is found to be an order of magnitude higher than shift that could be attributed to Joule heating. The current tuning of the resonator demonstrated here is of interest for miniature, self‐biased millimeter wave ferrite devices.