Electronic structure, magnetic ordering and X-ray magnetic circular dichroism in La_{1-x}Pr_{x}Co_{2}P_{2} phosphides

Bekenov Bekenov,Antonov Antonov,Moklyak Moklyak

doi:10.5488/cmp.18.33701

Abstract

The electronic structure and magnetic ordering in La$_{1-x}$Pr$_x$Co$_2$P$_2$ ($x=$0, 0.25, and 1) phosphides have been studied theoretically using the fully relativistic spin-polarized Dirac linear muffin-tin orbital (LMTO) band-structure method. The X-ray absorption and X-ray magnetic circular dichroism spectra at the Co$L_{2,3}$ and Pr$M_{4,5}$ edges have been investigated theoretically within the framework of the LSDA+$U$ method. The core-hole effect in the final state as well as the effects of the electric quadrupole $E_2$ and magnetic dipole $M_1$ transitions have been investigated. Good agreement with experimental measurements has been found.

Highlights

Ternary intermetallics AT2X2, where A − alkali, alkali-earth, rare-earth, or actinide metal, T − transition metal, and X − nonmetal, often demonstrate intrinsically complex magnetic structures and a wide variety of physical properties
The spin magnetic moments at the Pr and Co sites are aligned along the c axis with the antiparallel magnetic coupling between the neighboring planes resulting in antiferromagnetism
The E2 transitions are much weaker than the electric dipole transitions E1. They are almost invisible in the XAS and have a very small effect on the XMCD spectra at the Pr M4,5 edges

Summary

Introduction

Ternary intermetallics AT2X2, where A − alkali, alkali-earth, rare-earth, or actinide metal, T − transition metal, and X − nonmetal, often demonstrate intrinsically complex magnetic structures and a wide variety of physical properties They belong to the ThCr2Si2 structure type and can be conveniently represented as materials built by stacking covalently bonded transition metal-metalloid T2X2 layers, made of edge-sharing TX4 tetrahedra, with ionic A atoms. SmMn2Ge2 becomes ferromagnetic below 348 K and undergoes a transition to an antiferromagnetic state at 196 K, followed by a re-entrant ferromagnetic transition at 64 K [7] This peculiar magnetic behavior stems from the layered structure and the presence of two magnetic sublattices in these materials and was later observed for a number of rare-earth manganese germanides and silicides [8,9,10,11]. The isotypic phosphides were prepared much later [12] and the investigations of their magnetic properties have started only recently

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