Manipulation of topological spin configuration via tailoring thickness in van der Waals ferromagnetic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Fe</mml:mi><mml:mrow><mml:mn>5</mml:mn><mml:mtext>−</mml:mtext><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mi>Ge</mml:mi><mml:msub><mml:mi>Te</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>
Yang Gao, Shaohua Yan, Qiangwei Yin, He Huang, Zhuolin Li, Zhaozhao Zhu, Jianwang Cai, Baogen Shen, Hechang Lei, Ying Zhang, Shouguo Wang
Abstract
Topological spin textures with versatile configurations exhibit fascinating physical behavior as high-efficiency information units. Recent observations of nontrivial spin textures in two-dimensional (2D) van der Waals (vdW) ferromagnets have shed light on their functionality as a paradigm for spintronic devices. Here, the spin configuration of single-crystal 2D vdW ${\mathrm{Fe}}_{5\text{\ensuremath{-}}x}\mathrm{Ge}{\mathrm{Te}}_{2}$ is investigated by Lorentz transmission electron microscopy, where the conversion from Bloch-type bubbles to N\'eel-type skyrmions can be observed by tuning sample thickness. Remarkably, high-density N\'eel-type skyrmions can be obtained via field-cooling manipulation. We further demonstrate the underlying mechanism by varying the sample thickness and Dzyaloshinskii-Moriya interaction (DMI) parameters in a series of micromagnetic simulations, manifesting the presence of DMI at the ${\mathrm{Fe}}_{5\text{\ensuremath{-}}x}\mathrm{Ge}{\mathrm{Te}}_{2}$ surface by first-principles calculation. Our findings disclose the rich variety of topological spin textures in 2D vdW ${\mathrm{Fe}}_{5\text{\ensuremath{-}}x}\mathrm{Ge}{\mathrm{Te}}_{2}$, possessing great promise for future nonvolatile memories based on spin topology.