First-principles study on the half-metallic properties of the d quaternary Heusler compounds: KCaCBr and KCaCI

Jiangtao Du,Shengjie Dong,L.Y Wang,L.F Feng,X.T Wang,Hui Zhao

doi:10.1063/1.4966143

Abstract

With ab initio calculations, we studied the structural, electronic, and magnetic properties of quaternary Heusler compounds KCaCX (X = Br and I) adopted stable and metastable phases. We found that the most stable structure is type-3 atomic arrangement configuration where K, Ca, C, and X atoms occupy (0, 0, 0), (0.5, 0.5, 0.5), (0.25, 0.25, 0.25) and (0.75, 0.75, 0.75) positions, respectively. The metastable one is type-1 configuration where K, C, Ca and X occupy (0, 0, 0), (0.5, 0.5, 0.5), (0.25, 0.25, 0.25) and (0.75, 0.75, 0.75) positions, respectively. The results show that they are half-metallic ferromagnets with integer magnetic moments of 2.0 μB at their equilibrium lattice constants. It is also found that the spin-polarization is mainly from the C-2p states. In addition, KCaCBr compound with type-1 configuration shows an electronic transition from ordinary half-metallic state to zero-gap half-metallic state with the changing the lattice parameter.

Highlights

Half-metallic (HM) materials with different structures, including Heusler structures, binary compounds with rock-salt and zinc-blende structures,[1,2,3] have aroused much attention in the past few years due to 100 % spin polarization at the Fermi level where one spin channel is semiconducting or insulating behavior and the other is metallic character
Many works on d0 compounds with binary DO3 structure, ternary half-Heusler structure and full-Heusler structure, have been done theoretically.[9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]
Research and report on d0 HM compounds with quaternary Heusler structure is still rare

Summary

INTRODUCTION

Half-metallic (HM) materials with different structures, including Heusler structures, binary compounds with rock-salt and zinc-blende structures,[1,2,3] have aroused much attention in the past few years due to 100 % spin polarization at the Fermi level where one spin channel is semiconducting or insulating behavior and the other is metallic character. A novel HM compound, Fe2CoSi, with a conducting property in one spin channel and a zero band-gap in the other spin channel, was firstly theoretically proposed by Du et al.[4] This kind of material is defined as zero-gap half-metal and due to its special band-structure, it may possess a unique magnetoresistance behavior similar to spin-gapless semiconductor. Many works on d0 compounds with binary DO3 structure, ternary half-Heusler structure and full-Heusler structure, have been done theoretically.[9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26] research and report on d0 HM compounds with quaternary Heusler structure is still rare.

COMPUTATIONAL DETAILS

RESULTS AND DISCUSSION

CONCLUSIONS