Distribution of doped Mn at the \Sigma 3 (112) grain boundary in Ge

TL;DR

This study uses first-principles calculations to analyze how Mn atoms distribute and influence magnetism near grain boundaries in germanium, revealing minimal segregation and slight magnetic enhancement.

Contribution

It provides new insights into Mn behavior at Ge grain boundaries, showing non-uniform distribution and minimal segregation effects.

Findings

Substitutional sites are energetically favored over interstitial sites for Mn.

Mn distribution near the boundary is non-uniform with small segregation energy.

Magnetism of Mn-doped Ge is only slightly affected by grain boundary presence.

Abstract

Using first-principles density functional theory method, we have investigated the distribution and magnetism of doped Mn atoms in the vicinity of the 3 (112) grain boundary in Ge. We find that at low concentration, the substitutional sites are energetically favorable over the interstitial ones for Mn. The binding energy of Mn varies with lattice sites in the boundary region, and hence a non-uniform distribution of Mn nears the boundary. However, the average of their segregation energy is quite small, thus no remarkable grain boundary segregation of Mn is predicted. Due to volume expansion at the grain boundary, the spin polarization of Mn is slightly enhanced. Overall, we find that the magnetism of Mn-doped Ge is not sensitively dependent on the grain structure.