Magnetic anomalies in Nd₆Co_1.67Si₃: a first-order transition in the low-temperature isothermal magnetization behavior

Abstract

We present the results of magnetic measurements on Nd₆Co_1.67Si₃, a compound recently reported to crystallize in a hexagonal structure (space group P6₃/m) and to undergo long-range magnetic ordering below 84 K. The results reveal that the magnetism of this compound is quite complex with additional magnetic anomalies near 50 and 20 K. There are qualitative changes in the isothermal magnetization behavior with the variation of temperature. Notably, there is a field-induced spin reorientation as the temperature is lowered below 20 K. A finding we stress is that this transition is discontinuous for 1.8 K in the virgin curve, but the first-order character appears only after a field cycling for a narrow higher-temperature range near 5 K. Thus, this compound serves as an example for the stabilization of first-order transition induced by magnetic-field cycling. The issues of "phase coexistence" and "metastability" after a field cycling at low temperatures in this compound are also addressed.