High-frequency magnetic response of crystalline and nanocrystalline antiferromagnetic NiO

Performing micromagnetic simulations, we study the efficiency of response of bulk and polycrystalline nickel oxide (NiO) to high-frequency (up to 100 GHz) magnetic fields with relevance to potential application of the antiferromagnet as a core material to high-frequency coils and resonators. NiO is advantageous due to its insulating property and high Néel temperature. Though the dynamical susceptibility of the antiferromagnet is low, the achievable product of susceptibility and frequency (“performance factor”) appears to be relatively high, comparable to that of previously considered superferromagnetic systems. This makes NiO a potential core material for operating at extremely-high (sub-THz) frequency. The influence of thermal fluctuations on the susceptibility is estimated to be weak up to room temperature even for a nanocrystalline antiferromagnet, whereas, the magnetic response is linear for much wider ranges of frequencies and field amplitudes than for ferromagnetic and superferromagnetic systems.