First principles investigation of transition-metal doped group-IV semiconductors: R${_x}$Y$_{1-x}$ (R=Cr, Mn, Fe; Y=Si, Ge)

TL;DR

This study uses first principles calculations to explore magnetic interactions in transition-metal doped group-IV semiconductors, revealing diverse magnetic orders and mechanisms depending on dopant type and host material.

Contribution

It provides new insights into the magnetic ordering and microscopic mechanisms in TM-doped group-IV semiconductors, highlighting the complexity of ferromagnetism in these materials.

Findings

AFM order favored in Cr-doped Ge and Si at low concentrations

FM interaction dominates in Fe-doped Ge across all R-R distances

Different magnetic mechanisms identified for Mn-doped Ge and Si

Abstract

A number of transition-metal (TM) doped group-IV semiconductors, R$_{x}$Y$_{1-x}$ (R=Cr, Mn and Fe; Y=Si, Ge), have been studied by the first principles calculations. The obtained results show that antiferromagnetic (AFM) order is energetically more favored than ferromagnetic (FM) order in Cr-doped Ge and Si with $x$=0.03125 and 0.0625. In 6.25% Fe-doped Ge, FM interaction dominates in all range of the R-R distances while for Fe-doped Ge at 3.125% and Fe-doped Si at both concentrations of 3.125% and 6.25%, only in a short R-R range can the FM states exist. In the Mn-doped case, the RKKY-like mechanism seems to be suitable for the Ge host matrix, while for the Mn-doped Si, the short-range AFM interaction competes with the long-range FM interaction. The different origin of the magnetic orders in these diluted magnetic semiconductors (DMSs) makes the microscopic mechanism of the ferromagnetism in the DMSs more complex and attractive.