Magnetic susceptibility and magnetic-field behavior of CuB2O4 copper metaborate

An experimental study is reported regarding the temperature dependence of the magnetic susceptibility of a CuB(2)O(4) tetragonal single crystal within the 4.2-200-K range. It has been established that the magnetic susceptibility exhibits anomalies at 21 and 10 K and depends strongly on crystal orientation in the magnetic field. A study has been carried out of the field dependences of the magnetization of CuB(2)O(4) at various temperatures and crystal orientations. It is shown that for T > 21 K, the crystal is in a paramagnetic state determined by Cu(2+) copper ions with an effective magnetic moment of 1.77 mu(B). Within the 10-21 K interval, the field dependence of the magnetization is typical of a weak ferromagnet with magnetic moments of the two antiferromagnetically coupled sublattices lying in the tetragonal plane of the crystal. The spontaneous weakly-ferromagnetic moment is 0.56 emu/g at 10 K. The canting angle of the sublattice magnetic moments, determined by the Dzyaloshinski-Moriya interaction, is 0.49 degrees. It is believed that below 10 K, the CuB(2)O(4) crystal retains its easy-plane magnetic structure, but with a zero spontaneous magnetic moment. (C) 2000 MAIK "Nauka/Interperiodica".