Relaxational satellites of resonance absorption of a microwave field in CuCI2·2H2O in a tilted magnetic field

Two types of relaxational satellites of resonance isochrones in a constant magnetic field tilted with respect to the easy axis were studied experimentally and theoretically. It was established that the “whiskers” at higher resonance field at frequencies of 3.34, 2.99, 2.64, 2.48, 2.45, and 2.42 GHz and temperatures T = 1.5 − 1.7 K are linked with multiparticle absorption of the microwave field under conditions of strong suppression of the usual antiferromagnetic resonance as a result of dephasing of the microwave field and forced oscillations of the magnetic moments. The high sensitivity of such polarization satellites to the orientation of the magnetic field relative to the easy axis makes it possible to achieve highly accurate (to within 20”) mutual orientation of the crystal and the external magnetic field. The absorption “tails,” appearing on the isochrones in the region ψ > ψs after antiferromagnetic resonance (AFMR) is cut off, are associated with relaxation processes responsible for the broadening of the usual AFMR lines, and are manifested in the region of convexity of the resonance isogonic lines. A theoretical interpretation of the nature of the “whiskers” and absorption “tails” is given, and the reason for the vanishing of AFMR in the region of the spin-flop phase transition as ψ ⟶ 0 is explained.

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