Two‐Dimensional Ferromagnetism in Ultrathin MnSi Films

ABSTRACT 2D ferromagnets offer valuable insights into the fundamentals of magnetism and stimulate the progress of ultracompact spintronics. The demand for seamless integration of materials with 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 in the 2D limit. Here, we explore the magnetism of ultrathin films of MnSi on silicon. 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 film thickness. Metallic MnSi films demonstrate the anomalous Hall effect and negative magnetoresistance. Most importantly, the ferromagnetism of ultrathin MnSi films is consistent with the 2D character, as the effective Curie temperature depends on weak magnetic fields. The present study establishes ultrathin MnSi films as ferromagnets with prospective applications in silicon‐based spintronics.