Itinerant-electron metamagnetism of magnetocaloric material ErCo 2 and their borides

Abstract

The itinerant-electron metamagnetic transition of ErCo2 has been investigated as a function of a lattice constant. In order to control a lattice constant of ErCo2, we prepared several kinds of compounds including boron, ErCo2Bx. A considerable lattice expansion is observed, though the crystal structure of cubic C15 Laves phase is kept after increasing the concentration of boron up to x=0.1. In addition, the typical change of the curie temperature is enhanced from 35 to 65 K due to the volume expansion of ErCo2Bx. This result implies that the magnetic coupling is exclusively determined by the volume of the compound.