Electronic States, Spin-Orbit Coupling and Magnetism in Germanium 60{\deg} Dislocations

TL;DR

This study explores how 60° dislocations in germanium influence electronic, magnetic, and spin-orbit properties, revealing defect-induced bands, spin-orbit coupling effects, and potential for magnetic ordering, which could enable new device functionalities.

Contribution

It provides the first detailed analysis of electronic and magnetic effects, including spin-orbit coupling and antiferromagnetic ordering, induced by 60° dislocations in germanium using large-scale DFT calculations.

Findings

Defect-induced dispersive bands within the band gap near Γ point.

Observation of Rashba-Dresselhaus spin-orbit coupling effects.

Evidence of stable antiferromagnetic ordering with local magnetic moments.

Abstract

Defects in semiconductors have recently attracted renewed interest owing to their potential in novel quantum applications. Here we investigate the electronic and magnetic properties induced by 60{\deg} dislocations in Ge. Using large-scale DFT calculations, we determine the band structure for both the shuffle and glide sets in their lowest-energy configurations. We also perform charged-defect calculations to aid in the interpretation of complex photoluminescence spectra observed in epitaxial Ge layers. The band structure for the shuffle set reveals defect-induced dispersive bands localized within the band gap near the {\Gamma} point, whereas for the glide set, we observe strong overlap with the conduction band. Defect-induced band splitting evident away from {\Gamma} reveals Rashba-Dresselhaus spin-orbit coupling, an effect previously reported only for screw dislocations. Remarkably, we find evidence that specific dislocation arrangements can stabilize antiferromagnetic ordering with sizable local magnetic moments and considerable exchange splitting between opposite spin states. These results uncover rich physics in Ge dislocations through the combination of spin-orbit coupling and magnetic ordering, potentially enabling novel defect-based functionalities in Ge devices.