Pressure induced magnetic, electronic and mechanical properties of SmX (X = Se, Te)

Abstract

The magnetic, structural, elastic and electronic properties of Sm–chalcogenides in thestable and high pressure phase have been analyzed using an ab initio pseudo-potential method with aspin-polarized GGA based on exchange–correlation energy optimization, as implementedin SIESTA code. The magnetic phase stability has been determined from thetotal energy calculations in non-magnetic and magnetic phases, which clearlyindicate that at ambient and high pressures, these compounds are ferromagneticallystable. Also, the Sm ion is described in both five and six localized f electrons.Under compression the Sm chalcogenides undergo a first-order transformation fromSm2+ to a stablevalence state (Sm3+) with delocalization of the 4f electrons into the 5d states of Sm followed by a structuraltransition from the B1 to the B2 phase. The structural properties namely, equilibriumlattice constant, bulk modulus, its pressure derivative, transition pressure and volumecollapse agree well with the experimental results. We have also computed the electronicstructure at different volumes.