Effect of Confinement on Magnetism and Skyrmionic Properties of CoSi Nanoparticles*

Quantum-confinement and surface effects often result in unusual magnetic ordering, modified ordering temperatures, and different spin structures in nanoparticles as compared to the corresponding bulk alloys [1, 2]. In sharp contrast to non-magnetic bulk equiatomic CoSi, we show a magnetic ordering at room temperature with a net magnetic moment m = 0.11 μ_B/Co for CoSi nanoparticles. The nanoparticles have an average size of 11.6 nm, and crystallize in the cubic B20 structure, which supports spin spirals and skyrmions with broken helicity caused by non-zero Dzyaloshinskii–Moriya (DM) interactions [3]. DC susceptibility and anomalous Hall resistivity measurements are used to discuss the effect of confinement within the small diameter of CoSi nanoparticles on the room-temperature skyrmionic properties, which are essential for exploiting these complex spin structures for practical applications.
References
[1] B. Das, B. Balasubramanian, D.J. Sellmyer et al. Nano Letters, 16, 1132 (2016).
[2] B. Balasubramanian, R. Skomski, D.J. Sellmyer et al. Nanoscale, 10, 13011 (2018).
[3] B. Balasubramanian, R. Pahari, R. Skomski, D. J. Sellmyer et al. submitted.