Theory of Antiferromagnetic Resonance

Thermoinduced Magnetization in Nanoparticles of Antiferromagnetic Materials

“…The theoretical results have been confirmed in numerous experimental studies of antiferromagnetic resonance; see, for example, [21,22]. The relationship between the two angles can be written [20,21] …”

“…However, in antiferromagnetic materials, the excited states are more complex. Both classical and quantum mechanical calculations [20] show that the two sublattices are not strictly antiparallel, but precess in such a way that they make slightly different angles, A and B , with the easy direction of magnetization. This leads to precession frequencies, which are much higher than the typical frequencies of ferro-and ferrimagnetic resonances.…”

“…where g is the Landé factor, B is the Bohr magneton, k B is Boltzmann's constant, T is the temperature, and we have introduced the angular frequency of the precession [20,21] ! 0 h ÿ1 g B 2B a B E 1=2 .…”

Thermoinduced magnetization and uncompensated spins in antiferromagnetic nanoparticles

“…In a perfect antiferromagnetic material the relationship between the precession angles of the two sublattices can be written as 12,13 sin 1 sin 2 = 1 ± ␦.…”

“…Here ␦ Ϸ ͱ 2B a / B E , where B E = 0 12 S / V is the exchange field, 12 is the exchange constant, and B a = KV / S is the anisotropy field. In order to extend the calculation to a particle with a small uncompensated moment, we treat the system as that of a ferrimagnet, but in the limit where the difference between the sublattice magnetic moments is very small.…”