Torque magnetometry study of metamagnetic transitions in single-crystal HoNi(2)B(2)C at T approximate to 1.9 K

Abstract

Metamagnetic transitions in single-crystal rare-earth nickel borocarbide HoNi(2)B(2)C have been studied at T approximate to 1.9 K with a Quantum Design torque magnetometer. This compound is highly anisotropic with a variety of metamagnetic states at low temperature which includes antiferromagnetic, ferrimagnetic, noncollinear, and ferromagnetic-like (saturated paramagnet) states. The critical fields of the transitions depend crucially on the angle theta between applied field and the easy axis [110]. Measurements of torque along the c-axis have been made while changing the angular direction of the magnetic field (parallel to basal tetragonal ab planes) and with changing field at fixed angle over a wide angular range. Two new phase boundaries in the region of the noncollinear phase have been observed, and the direction of the magnetization in this phase has been precisely determined. At low field the antiferromagnetic phase is observed to be multidomain. In the angular range very close to the hard axis [100] (-6(degrees)less than or similar to phi less than or similar to 6(degrees), where phi is the angle between field and the hard axis) the magnetic behavior is found to be "frustrated" with a mixture of phases with different directions of the magnetization.