Signatures of electron-boson coupling in half-metallic ferromagnet Mn$_5$Ge$_3$: study of electron self-energy $\Sigma(\omega)$ obtained from infrared spectroscopy

TL;DR

This study uses infrared and optical spectroscopy to analyze the electron self-energy in Mn$_5$Ge$_3$, revealing electron-boson coupling possibly related to magnetic modes, which advances understanding of electron correlations in this half-metallic ferromagnet.

Contribution

It introduces novel numerical algorithms to extract electron self-energy from optical data, providing new insights into electron-boson interactions in Mn$_5$Ge$_3$.

Findings

Evidence of electron-boson coupling in Mn$_5$Ge$_3$

Charge carriers possibly coupled to magnetic bosonic modes

Enhanced understanding of electron correlations in half-metallic ferromagnets

Abstract

We report results of our infrared and optical spectroscopy study of a half-metallic ferromagnet Mn$_5$Ge$_3$. This compound is currently being investigated as a potential injector of spin polarized currents into germanium. Infrared measurements have been performed over a broad frequency (50 - 50000 cm$^{-1}$) and temperature (10 - 300 K) range. From the complex optical conductivity $\sigma(\omega)$ we extract the electron self-energy $\Sigma(\omega)$. The calculation of $\Sigma(\omega)$ is based on novel numerical algorithms for solution of systems of non-linear equations. The obtained self-energy provides a new insight into electron correlations in Mn$_5$Ge$_3$. In particular, it reveals that charge carriers may be coupled to bosonic modes, possibly of magnetic origin.