Critical Sample Aspect Ratio and Magnetic Field Dependence for Antiskyrmion Formation in Mn1.4PtSn Single-Crystals

Abstract

Mn1.4PtSn is the first material in which antiskyrmions have been observed in ultra-thin single crystalline specimens. While bulk crystals exhibit fractal patterns of purely ferromagnetic domain ordering at room temperature, ultra-thin Mn1.4PtSn lamellae clearly show antiskyrmion lattices with lattice spacings up to several $\hat{I}¼$m. In the work presented here, we systematically investigate the thickness region from 400 nm to 10 $\hat{I}¼$m using 100 $\times$ 100 $\hat{I}¼$m${}^2$ -wide Mn1.4PtSn plates, and identify the critical thickness-to-width aspect ratio $\hat{I}{\pm }_0=0.044$ for the ferromagnetic fractal domain to the non-collinear texture phase transition. Additionally, we also explore these non-collinear magnetic textures below the critical aspect ratio $\hat{I}{\pm }_0$ above and below the spin-reorientation transition temperature $T_{SR}$ while applying variable external magnetic fields. What we find is a strong hysteresis for the occurrence of an antiskyrmion lattice, since the antiskyrmions preferentially nucleate by pinching them off from helical stripes in the transition to the field polarized state.