Half metallic digital ferromagnetic heterostructure composed of a $\delta$-doped layer of Mn in Si

TL;DR

This paper investigates a Si-based heterostructure with a Mn delta-doped layer, revealing it as a two-dimensional half-metallic ferromagnet with potential for spintronic devices.

Contribution

It introduces a novel Si-based heterostructure with delta-doped Mn layer exhibiting half-metallicity and ferromagnetism, analyzed through ab initio methods.

Findings

Heterostructure is energetically ferromagnetic over antiferromagnetic.

System exhibits two-dimensional half-metallic behavior.

Minority-spin gap of 0.25 eV and potential high Curie temperature.

Abstract

We propose and investigate the properties of a digital ferromagnetic heterostructure (DFH) consisting of a $\delta$-doped layer of Mn in Si, using \textit{ab initio} electronic-structure methods. We find that (i) ferromagnetic order of the Mn layer is energetically favorable relative to antiferromagnetic, and (ii) the heterostructure is a two-dimensional half metallic system. The metallic behavior is contributed by three majority-spin bands originating from hybridized Mn-$d$ and nearest-neighbor Si-$p$ states, and the corresponding carriers are responsible for the ferromagnetic order in the Mn layer. The minority-spin channel has a calculated semiconducting gap of 0.25 eV. Analysis of the total and partial densities of states, band structure, Fermi surfaces and associated charge density reveals the marked two-dimensional nature of the half metallicity. The band lineup is found to be favorable for retaining the half metal character to near the Curie temperature ($T_{C}$). Being Si based and possibly having a high $T_{C}$ as suggested by an experiment on dilutely doped Mn in Si, the heterostructure may be of special interest for integration into mature Si technologies for spintronic applications.