Density-functional theory study of half-metallic heterostructures: interstitial Mn in Si

TL;DR

This study uses density-functional theory to show that Si-based heterostructures with interstitial Mn doping are half-metallic and have high spin polarization, offering new possibilities for Si spintronics.

Contribution

It demonstrates that interstitial Mn in Si heterostructures can induce half-metallicity and high spin polarization, challenging previous focus on substitutional Mn.

Findings

Si heterostructures with 1/4 layer interstitial Mn are half-metallic.

High spin polarization (~85%) at 1/2 Mn concentration.

Interstitial Mn heterostructures are more stable than substitutional Mn layers.

Abstract

Using density-functional theory within the generalized gradient approximation, we show that Si-based heterostructures with 1/4 layer $\delta$-doping of {\em interstitial} Mn (Mn$_{\mathrm int}$) are half-metallic. For Mn$_{\mathrm int}$ concentrations of 1/2 or 1 layer, the states induced in the band gap of $\delta$-doped heterostructures still display high spin polarization, about 85% and 60%, respectively. The proposed heterostructures are more stable than previously assumed $\delta$-layers of {\em substitutional} Mn. Contrary to wide-spread belief, the present study demonstrates that {\em interstitial} Mn can be utilized to tune the magnetic properties of Si, and thus provides a new clue for Si-based spintronics materials.