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

TL;DR

This study investigates the formation of antiskyrmions in Mn1.4PtSn single crystals, identifying critical aspect ratios and magnetic field effects that influence non-collinear magnetic textures in ultra-thin specimens.

Contribution

It systematically analyzes the critical thickness-to-width ratio for antiskyrmion formation and explores magnetic field effects on these textures below the critical aspect ratio.

Findings

Critical aspect ratio for phase transition identified as 0.044.

Antiskyrmions nucleate via pinching off from helical stripes.

Strong hysteresis observed in antiskyrmion lattice formation.

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 $\mu$m. In the work presented here, we systematically investigate the thickness region from 400 nm to 10 $\mu$m using 100 $\times$ 100 $\mu$m$^2$ -wide Mn1.4PtSn plates, and identify the critical thickness-to-width aspect ratio $\alpha_0 = 0.044$ 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 $\alpha_0$ 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.