We examine the surface size- and shape-effects of soliton annihilation and soliton nucleation in chiral magnet CrNb3S6. We measure magnetization (M) curves of submillimeter-sized single crystals with an equal length along the c-axis (Lc = 10 μm) but with different cross sections in the ab-plane (Sab = 0.120-0.014 mm2). We find a ferromagnetic type of magnetizing (FMM) with a convex curve (d2M/dH2 < 0) near zero field (H = 0) and a major jump in M near the forced ferromagnetic state, which are more conspicuous, compared with earlier samples with submillimeter Lc [K. Tsuruta et al. J. Phys. Soc. Jpn. 85, 013707 (2016)]. A new finding is that the major jump in M occurs at lower fields in samples with the smaller Sab. We further perform numerical simulation of the magnetization process with the Landau-Lifshitz-Gilbert equation of the Langevin-type. Based on the numerical results, we attribute the FMM at small fields to rapid annihilation of soliton assisted by the reduction of Dzyaloshinskii-Moriya interaction near the surfaces. We also discuss possible penetration processes of chiral soliton through the ac-(bc-)plane as well as ab-plane, and its relation to the major jump in M. Our experimental and calculated results will contribute to understanding of the effects of topological metastability in chiral magnets.
ASJC Scopus subject areas
- General Physics and Astronomy