Atomic layer doping of Mn magnetic impurities from surface chains at a Ge/Si hetero-interface

TL;DR

This paper demonstrates a novel Mn delta-doping technique at Ge/Si interfaces using atomic chains, revealing stable one-dimensional structures and magnetic ordering around 120 K, with potential for advanced spintronic applications.

Contribution

It introduces a surface chain-based Mn delta-doping method that prevents silicide formation and enables magnetic ordering at relatively high temperatures.

Findings

Mn atoms occupy substitutional sites as shown by DFT.

Stable one-dimensional Mn structures are achieved at room temperature.

Magnetic ordering occurs around 120 K in the doped layer.

Abstract

We realize Mn $\delta$-doping into Si and Si/Ge interfaces using Mn atomic chains on Si(001). Highly sensitive X-ray absorption fine structure techniques reveal that encapsulation at room temperature prevents the formation of silicides / germanides whilst maintaining one dimensional anisotropic structures. This is revealed by studying both the incident X-ray polarization dependence and post-annealing effects. Density functional theory calculations suggest that Mn atoms are located at substitutional sites, and show good agreement with experiment. A comprehensive magnetotransport study reveals magnetic ordering within the Mn $\delta$-doped layer, which is present at around 120\,K. We demonstrate that doping methods based on the burial of surface nanostructures allows for the realization of systems for which conventional doping methods fail.