Electronic Structure of Samarium Monopnictides and Monochalcogenides

TL;DR

This paper investigates the electronic structures of samarium monopnictides and monochalcogenides using self-interaction corrected density functional theory, revealing different valence states and phase transitions under pressure.

Contribution

It applies a self-interaction corrected local-spin density approach to compare localized f-electron scenarios, elucidating valence states and phase transitions in SmX compounds.

Findings

Five localized f-electrons lead to intermediate valence in pnictides and SmO.

Six localized f-electrons produce semiconducting behavior in chalcogenides.

Under pressure, Sm chalcogenides undergo first-order transitions with f-electron destabilization.

Abstract

The electronic structures of SmX (X=N, P, As, Sb, Bi, O, S, Se, Te, Po)compounds are calculated using the self-interaction corrected local-spin density approximation. The Sm ion is described with either five or six localized $f$-electrons while the remaining electrons form bands, and the total energies of these scenarios are compared. With five localized $f$-electrons a narrow $f$-band is formed in the vicinity of the Fermi level leading to an effective intermediate valence. This scenario is the ground state of all the pnictides as well as SmO. With six localized $f$-electrons, the chalcogenides are semiconductors, which is the ground state of SmS, SmSe and SmTe. Under compression the Sm chalcogenides undergo first order transitions with destabilization of the $f$ states into the intermediate valence state, the bonding properties of which are well reproduced by the present theory.