Magnetic, Electronic, and Mechanical Properties of Strongly Correlated Samarium Mono-chalcogenides under High Pressure

The magnetic, structural, electronic and optical properties of Sm-chalcogenides in the stable Fm (3) over barm and high-pressure Pm (3) over barm phase have been analyzed by means of ab-initio pseudo-potential method within the framework of density functional theory. The spin polarized GGA based on exchange-correlation energy optimization has been used for calculating the total energy as implemented in SIESTA code. The magnetic phase stability was determined from the total energy calculations for both the non-magnetic and magnetic phases, which clearly indicate that at ambient and high pressures, these compounds are ferromagnetically stable. Also, the Sm ion is considered with five and six localized f electrons. Under compression the Sm chalcogenides undergo first-order transition from Sm2+ to mixed valent Sm3+ due to the delocalization of 4f electrons into 5d states of Sm followed by a structural transition from B1 to B2 phase. The structural properties viz., equilibrium lattice constant, bulk modulus, its pressure derivative, transition pressure and volume collapse agree well with the experimental results. Electronic structures at different volumes have also computed.