Tuning of exchange constants and magnetic anisotropy for terahertz antiferromagnetic resonance frequencies in cation-doped NiO

Advances in communication technology have moved carrier frequencies to the terahertz (THz) regime where the conventional microwave technologies and materials cannot work as their physical properties no longer respond to such frequencies. Antiferromagnets are materials whose magnetic properties respond and interact with THz-frequency electromagnetic waves. Phenomenologically, the response frequency is readily determined by the exchange energy and the magnetic anisotropy. In this paper, we revisit the antiferromagnetic resonance frequency of NiO, an archetypical antiferromagnetic material, and study the effect of cation doping (such as Li, Na, Be, Mg, Mn, Fe, and Zn) on its resonance frequency by first-principles calculations. The cation-dependent tunings of the exchange constant and magnetic anisotropy are demonstrated, with the resonance frequency varying from a minimum of $0.77$ THz by Li doping to a maximum of $1.60$ THz by Fe doping, referenced to a value of $1.20$ THz obtained for pure NiO. Our findings encourage exploring of antiferromagnetic materials for future THz spintronic applications.