Instability of skyrmions in magnetic fields

Abstract

In this combined experimental and theoretical work, we report on the evolution of the skyrmion radius and its destruction in the system Co/Ru(0001) when an out-of-plane magnetic field is applied. At low fields, skyrmions are metastable and display an elliptical instability in which along the short axis, the spin texture approaches that of the spin-spiral phase and the long axis expands in order to go back to the spin-spiral ground state. At high fields, we observe round skyrmions of finite size up to the collapse field B c , where they are destroyed and the topological charge is annihilated. We estimate B c via numerical methods based on magnetization dynamics simulations parametrized by density functional theory calculations and compare it to experimental scanning tunneling microscopy observations obtained at % 30 mK.

Emergence of Nontrivial Spin Textures in Frustrated Van Der Waals Ferromagnets

“…The magnetic field dependence of the changes in shape suggests that the MS is unstable at low intensities of the external applied field. This agrees with the recent experimental observation of metastable skyrmions in the Co/Ru bilayer when low magnetic fields are applied in the out-of-plane direction [ 104 ]. It is therefore plausible that the MS can be displaced at low current densities.…”

Majorana bound states in magnetic skyrmions imposed onto a superconductor

“…Already now, magnetic bilayer systems hosting skyrmions are available. In addition, there is ongoing progress towards the observation of skyrmions below the superconducting transition temperature in such bilayers [75]. In order to generate skyrmion-vortex pairs rather than bare skyrmions, the superconducting layer should preferably be a type-II superconductor.…”

Stacking influence on the in-plane magnetic anisotropy in a 2D magnetic system

“…Ab-initio calculations 5,18 have shown that the spin reorientation transitions arise from a combination of strain and surface effects. Recent work has taken advantage of the low magnetocrystalline anisotropy of the monolayer-thick Co films on Ru(0001) to study skyrmion formation under low magnetic fields 19,20 or even proximity supercon-ductivity effects 21 , promoting Co films a few atomic layers thick on ruthenium as a novel quantum material.…”

“…Cobalt layers a few atoms thick on Ru(0001) are 2D-magnetic systems that present long range order: a film one atomic layer thick has a Curie temperature of 200 K and in-plane magnetization, films two atoms thick have a Curie temperature of 500 K and out-of-plane magnetization, and films three atoms thick have again an in-plane magnetization and a Curie temperature above 600 K. 5 Ab initio calculations 5,18 have shown that the spin reorientation transitions arise from a combination of strain and surface effects. Recent work has taken advantage of the low magnetocrystalline anisotropy of the monolayer-thick Co films on Ru(0001) to study skyrmion formation under low magnetic fields 19,20 or even proximity superconductivity effects, 21 promoting Co films a few atomic layers thick on ruthenium as a novel quantum material.…”