MAGNETIC-FIELD-INDUCED TRANSITIONS IN MN5SI3

The magnetic properties of the intermetallic compound Mn5Si3 with D8(8)-type crystallographic ordering have been investigated at high fields and low temperatures. Magnetisation measurements in fields up to 12 T reveal that it is possible to induce transitions from the low temperature non-collinear antiferromagnetic phase by the application of a critical field which reduces in an approximately quadratic fashion with increasing temperature. The transition takes place over a field range of about 4 T wide and is accompanied by a large increase in susceptibility and hysteresis. At higher fields the behaviour seems to be unsaturated and similar to that observed for the collinear antiferromagnetic phase which is stable in the range 70-95 K. In addition, for both phases another transition which appears to be of second order occurs at a much smaller field involving a decrease in susceptibility for the non-collinear phase and an increase in susceptibility for the collinear phase.