Spin Textures induced by Quenched Disorder in a Reentrant Spin Glass: Vortices versus "Frustrated" Skyrmions

Abstract

Reentrant spin glasses are frustrated disordered ferromagnets developing vortex-like textures under an applied magnetic field. Our study of a Ni${}_{0.81}$Mn${}_{0.19}$ single crystal by small angle neutron scattering clarifies their internal structure and shows that these textures are randomly distributed. Spin components transverse to the magnetic field rotate over length scales of 3-15 nm in the explored field range, decreasing as field increases according to a scaling law. Monte-Carlo simulations reveal that the internal structure of the vortices is strongly distorted and differs from that assumed for "frustrated" skyrmions, built upon a competition between symmetric exchange interactions. Isolated vortices have small non-integer topological charge. The vortices keep an anisotropic shape on a 3 dimensional lattice, recalling "croutons" in a "ferromagnetic soup". Their size and number can be tuned independently by the magnetic field and concentration x (or heat treatment), respectively. This opens an original route to understand and control the influence of quenched disorder in systems hosting non trivial spin textures.

arXiv comment23 pages, 15 figures, includes supplement

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• Microstructural-defect-induced Dzyaloshinskii-Moriya interaction
• Evolution of helimagnetic correlations in Mn${}_{1-x}$Fe${}_x$Si with doping: a small-angle neutron scattering study
• Fingerprint of vortex-like flux closure in isotropic Nd-Fe-B bulk magnet
• Experimental observation of third-order effect in magnetic small-angle neutron scattering
• Neutron study of magnetic correlations in rare-earth-free Mn-Bi magnets
• Magnetic phase diagram and cluster glass-like properties of stage-1 graphite intercalated FeCl${}_3$
• Defect-induced spin textures in magnetic solids
• Probing Random-Bond Disorder Effects on Ferromagnetic Skyrmion Arrays