Two-Dimensional Ferromagnetism in Monolayers of MnSi

TL;DR

This study demonstrates that monolayer MnSi films exhibit robust two-dimensional ferromagnetism with potential for silicon-based spintronics applications.

Contribution

It reveals the magnetic properties of ultrathin MnSi films, establishing them as 2D ferromagnets suitable for integration with silicon technology.

Findings

Exchange splitting observed in MnSi bands.

Ferromagnetism persists down to monolayer thickness.

Ultrathin MnSi becomes insulating below 3 monolayers.

Abstract

2D ferromagnets offer valuable insights into the fundamentals of magnetism and stimulate the progress of ultracompact spintronics. The demand for seamless integration of the materials with the Si technology, particularly helpful to their applications in nanoelectronics, draws attention to 2D magnetic silicides. MnSi is a prominent silicide hosting magnetic phases with unconventional properties; however, little is known about magnetic states of MnSi at the 2D limit. Here, we explore the magnetism of ultrathin films of MnSi on silicon, down to a single monolayer. Angle-resolved photoemission spectra suggest exchange splitting of MnSi bands. Magnetization measurements confirm that the ferromagnetic state in MnSi is rather robust with respect to the number of monolayers. Thick metallic films demonstrate the anomalous Hall effect and negative magnetoresistance; however, as the number of monolayers drops below 3, MnSi becomes an insulator. Most importantly, the ferromagnetism of ultrathin MnSi films acquires a 2D character, as its effective Curie temperature depends on weak magnetic fields. The present study establishes MnSi monolayers as 2D ferromagnets that can find potential applications in silicon-based spintronics.