Magnetism of CoSi Nanoparticles with B20-Type Structure*

Magnetic nanoparticles or clusters often exhibit novel magnetic properties compared to isostructural bulk alloys due to low-dimensional and quantum-confinement effects.^1,2 Magnetic materials with noncentrosymmetric B20 cubic structure have attracted much interest due to skyrmion spin structures originating from Dzyaloshinskii-Moriya interactions.³ We have used a cluster-deposition method to fabricate CoSi nanoparticles having an average size of 10 nm with an rms standard deviation of σ/d ≈0.10, and investigated their magnetic properties by experiments and first-principle DFT calculations. The X-ray diffraction pattern shows the formation of a B20-type cubic structure in CoSi nanoparticles, similar to bulk alloy. In sharp contrast to bulk CoSi, which is paramagnetic down to 4 K , our experimental results and DFT calculations show a net magnetic moment of about 0.2 μ_B/Co for the nanoparticles. Nanoscale effects on the magnetism of CoSi, including complex DM interactions, will be presented.
References
¹ B. Balasubramanian et al. Appl. Phys. Lett. 108, 152406 (2016).
²B. Das et al. Nano Lett. 16, 1132 (2016).
³N. Nagaosa and Y. Tokura, Nat. Nanotech. 8, 899 (2013).