Magnetism on the boron-doped Si(111)-$\sqrt 3 \times \sqrt 3$ surface

TL;DR

This study uses first-principles calculations to explore magnetism on boron-doped Si(111) surfaces, revealing defect-induced local magnetic moments and potential for ferromagnetic stabilization relevant to spintronics.

Contribution

It demonstrates how defect structures on boron-doped Si(111) surfaces can induce and stabilize magnetic moments, highlighting a new pathway for spintronic applications.

Findings

Defect structures generate local magnetic moments of 2 μ_B.

Adjacent defects tend to align antiferromagnetically.

Electron adjustment can stabilize ferromagnetism.

Abstract

We investigate the possible magnetism on the Si(111)-$\sqrt 3 \times \sqrt 3$ surface, which is stabilized for highly boron-doped samples, by using first-principles calculations. When the silicon adatom on top of a boron atom is removed to form a defect structure, three silicon dangling bonds are exposed generating half-filled doubly degenerate energy levels in the band gap which stabilizes a local magnetic moment of 2 $\mu_{\rm B}$. When there are many such defect structures adjacent one another, they are found to align antiferromagnetically. However, we demonstrate that the ferromagnetism can be stabilized by adjusting the number of electrons in defects, suggesting a possibility towards spintronic applications of this unique silicon surface structure.