Giant magnetocaloric (GMC) materials constitute a requirement for near room temperature magnetic refrigeration. (Fe,Mn)2(P,Si) is a GMC compound with strong magnetoelastic coupling. The main hindrance towards application of this material is a comparably large temperature hysteresis, which can be reduced by metal site substitution with a nonmagnetic element. However, the (Fe,Mn)2(P,Si) compound has two equally populated metal sites, the tetrahedrally coordinated 3f and the pyramidally coordinated 3g sites. The magnetic and magnetocaloric properties of such compounds are highly sensitive to the site specific occupancy of the magnetic atoms. Here we have attempted to study separately the effect of 3f and 3g site substitution with equal amounts of vanadium. Using formation energy calculations, the site preference of vanadium and its influence on the magnetic phase formation are described. A large difference in the isothermal entropy change (as high as 44\%) with substitution in the 3f and 3g sites is observed. The role of the lattice parameter change with temperature and the strength of the magnetoelastic coupling on the magnetic properties are highlighted.
@article{arxiv.2209.14962,
title = {Site-specific atomic substitution in a giant magnetocaloric Fe$_2$P-type system},
author = {Sagar Ghorai and Johan Cedervall and Rebecca Clulow and Shuo Huang and Tore Ericsson and Lennart Häggström and Vitalii Shtender and Erna K. Delczeg-Czirjak and Levente Vitos and Olle Eriksson and Martin Sahlberg and Peter Svedlindh},
journal= {arXiv preprint arXiv:2209.14962},
year = {2023}
}