Strongly Enhanced Curie Temperature in Carbon-Doped Mn5Ge3 Films

TL;DR

This study demonstrates that carbon doping in Mn5Ge3 films significantly increases the Curie temperature, with structural analysis indicating interstitial carbon enhances ferromagnetic stability through lattice compression and electronic structure modification.

Contribution

It reveals a novel method of enhancing Curie temperature in Mn5Ge3 films via carbon interstitial doping and structural modification.

Findings

Curie temperature increased to 440 K with x >= 0.5

Carbon is incorporated interstitially, causing lattice compression

Enhanced ferromagnetic stability linked to electronic structure changes

Abstract

The structural and magnetic properties of Mn5Ge3Cx films prepared at elevated substrate temperatures TS are investigated. In particular, films with x >= 0.5 and TS = 680 K exhibit a strongly enhanced Curie temperature TC = 440 K compared to Mn5Ge3 with TC = 304 K. Structural analysis of these films suggests that the carbon is interstitially incorporated into the voids of Mn octahedra of the hexagonal Mn5Si3-type structure giving rise to a lattice compression. The enhanced ferromagnetic stability in connection with the lattice compression is interpreted in terms of an Mn-Mn interaction mediated by C based on a change in the electronic structure.