Magnetic properties of the half-metallic Heusler alloysCo2VAlandCo2VGaunder pressure

Abstract

Magnetization measurements have been carried out at high pressure up to 12.1 kbar for ${\text{Co}}_{2}\text{VAl}$ and ${\text{Co}}_{2}\text{VGa}$ with a miniature high-pressure clamp cell. The magnetic moment measured at 5 K is independent of pressure for ${\text{Co}}_{2}\text{VGa}$. This is an experimental observation that gives clear evidence that ${\text{Co}}_{2}\text{VGa}$ possesses half-metallic electronic structure. On the other hand, a sizable pressure dependence of the magnetic moment is observed for ${\text{Co}}_{2}\text{VAl}$ and it is attributed to the precipitation of the bcc particles in the matrix $L{2}_{1}$ phase. The Curie temperature decreases with increasing pressure for ${\text{Co}}_{2}\text{VGa}$, reflecting characteristics typical for usual itinerant electron systems. The negative pressure dependence of the Curie temperature found in ${\text{Co}}_{2}\text{VGa}$ contrasts fairly with that of other Heusler alloys containing Mn atoms.