Torque magnetometry studies of metamagnetic transitions in single-crystal HoNi2B2C and ErNi2B2C at T≈1.9 K.

The metamagnetic transitions in single-crystal rare-earth nickel borocarbide HoNi2B2C and ErNi2B2C have been studied at 1.9 K with a Quantum Design torque magnetometer. The critical fields of the transitions depend crucially on the angle between applied field and the easy axis [110] for HoNi2B2C and [100] for ErNi2B2C. Torque measurements have been made while changing angular direction of the magnetic field (parallel to basal tetragonal ab planes) in a wide angular range (more than two quadrants). The results are used not only to check and refine the angular diagram for metamagnetic transitions in these compounds, but also to find new features of the metamagnetic states. Among new results for the Ho borocarbide are the influence of a multidomain antiferromagnetic state, and “frustrated” behavior of the magnetic system for field directions close to the hard axis [100]. Torque measurements of the Er borocarbide clearly show that the sequence of metamagnetic transitions with increasing field (and the corresponding number of metamagnetic states) depends on the angular direction of the magnetic field relative to the easy axis. [ABSTRACT FROM AUTHOR]