Antiferromagnetic resonance in CuB2O4 single crystal

The frequency-field, temperature, and angular dependences of the antiferromagnetic resonance parameters for the tetragonal CuB2O4 single crystal are studied in the frequency range 2.6-80 GHz and at temperatures of 4.2-30 K. The results obtained confirm the fact that, in the high-temperature state in the range 10-21 K, this compound is an easy-plane weak ferromagnet. The temperature dependence of the Dzyaloshinski field is determined. An abrupt change observed in the frequency-field dependence of the magnetic resonance at T = 4.2 K and H perpendicular to C-4 indicates the transition to the weak ferromagnetic state induced by the external field H-perpendicular to. The phase diagram for CuB2O4 is constructed on the H-perpendicular to-T coordinates. It is demonstrated that, in the low-temperature state, the magnetic moments of copper ions remain in the basal plane, but the weak ferromagnetism is absent. (C) 2000 MAIK "Nauka/Interperiodica".