Phase Selection in Mn-Si Alloys by Fast Solid-State Reaction with Enhanced Skyrmion Stability

B20-type transition-metal silicides or germanides are noncentrosymmetric materials hosting magnetic skyrmions, which are promising information carriers in spintronic devices. The prerequisite is to prepare thin films on technology-relevant substrates with magnetic skyrmions stabilized at a broad temperature and magnetic-field working window. A canonical example is the B20-MnSi film grown on Si substrates. However, the as-yet unavoidable contamination with MnSi1.7 occurs due to the lower nucleation temperature of this phase. In this work, a simple and efficient method to overcome this problem and prepare single-phase MnSi films on Si substrates is reported. It is based on the millisecond reaction between metallic Mn and Si using flash-lamp annealing (FLA). By controlling the FLA energy density, single-phase MnSi or MnSi1.7 or their mixture can be grown at will. Compared with bulk MnSi, the prepared MnSi films show an increased Curie temperature of up to 41 K. In particular, the magnetic skyrmions are stable over a much wider temperature and magnetic-field range than reported previously. The results constitute a novel phase selection approach for alloys and can help to enhance specific functional properties, such as the stability of magnetic skyrmions.

Automated summary

The study presents a simple and efficient method to prepare single-phase MnSi films on Si substrates by utilizing flash-lamp annealing. By controlling the energy density of the annealing process, the growth of single-phase MnSi, MnSi1.7, or their mixture can be achieved. The prepared MnSi films exhibit an increased Curie temperature and stable magnetic skyrmions over a wider temperature and magnetic-field range compared to bulk MnSi, showing promise for enhancing specific functional properties such as skyrmion stability.