Magnetic properties of Mn-doped Ge46 and Ba8Ge46 clathrates

TL;DR

This study uses density functional theory to explore the magnetic properties of Mn-doped Ge46 and Ba8Ge46 clathrates, revealing ferromagnetic ground states driven by hybridization and RKKY interactions, aligning with experimental data.

Contribution

It provides a detailed theoretical analysis of magnetic interactions in Mn-doped Ge46 and Ba8Ge46 clathrates, highlighting mechanisms behind ferromagnetism in these materials.

Findings

Ferromagnetic ground states are possible in both compounds.

Hybridization induces negative exchange splitting in Mn2Ge44.

RKKY-like interactions occur in Ba8Ge46 due to conduction electrons.

Abstract

We present a detailed study of the magnetic properties of unique cluster assembled solids namely Mn doped Ge46 and Ba8Ge46 clathrates using density functional theory. We find that ferromagnetic (FM) ground states may be realized in both the compounds when doped with Mn. In Mn2Ge44, ferromagnetism is driven by hybridization induced negative exchange splitting, a generic mechanism operating in many diluted magnetic semiconductors. However, for Mn-doped Ba8Ge46 clathrates incorporation of conduction electrons via Ba encapsulation results in RKKY-like magnetic interactions between the Mn ions. We show that our results are consistent with the major experimental observations for this system.