Magnetic behaviour and magnetostriction of TbxY1-xMn2 intermetallics

Abstract

The spontaneous magnetic behaviour and the stability of the magnetic moment on the Mn atoms versus temperature, with concentration, and under applied magnetic held and pressure in the series TbxY1-xMn2 have been investigated by means of magnetostriction up to 14 T, AC susceptibility under pressure up to 7 kbar and linear thermal expansion measurements. Large volume anomalies were observed in all compounds of the series at TN, the temperature at which the Mn magnetic moments become local. TN remains almost constant for x>or=0.2. Below TN the magnetic structure of Tb-rich compounds is unstable under applied magnetic field and the Mn magnetic moments can be reverted to itineracy. The obtained results can be explained on the assumption that the transition is non-homogeneous and consequently a small part of the sample does not transform, remaining without Mn local magnetic moments below TN. This region grows either under applied field or under applied pressure and it can occupy the whole sample. From these results a magnetic phase diagram of this series is proposed.