Controllable Skyrmionic Phase Transition between Néel Skyrmions and Bloch Skyrmionic Bubbles in van der Waals Ferromagnet Fe3-δ GeTe2

Chen Liu; Jiawei Jiang; Chenhui Zhang; Qingping Wang; Huai Zhang; Dongxing Zheng; Yan Li; Yinchang Ma; Hanin Algaidi; Xingsen Gao; Zhipeng Hou; Wenbo Mi; Jun-Ming Liu; Ziqiang Qiu; Xixiang Zhang

doi:10.1002/advs.202303443

Controllable Skyrmionic Phase Transition between Néel Skyrmions and Bloch Skyrmionic Bubbles in van der Waals Ferromagnet Fe_3-δ GeTe₂

Adv Sci (Weinh). 2023 Sep;10(27):e2303443. doi: 10.1002/advs.202303443. Epub 2023 Jul 28.

Authors

Chen Liu¹, Jiawei Jiang², Chenhui Zhang¹, Qingping Wang^{3

4}, Huai Zhang⁴, Dongxing Zheng¹, Yan Li¹, Yinchang Ma¹, Hanin Algaidi¹, Xingsen Gao⁴, Zhipeng Hou⁴, Wenbo Mi², Jun-Ming Liu^{4

5}, Ziqiang Qiu⁶, Xixiang Zhang¹

Affiliations

¹ Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
² Tianjin Key Laboratory of Low-Dimensional Materials Physics and Preparation Technology, School of Science, Tianjin University, Tianjin, 300354, China.
³ College of Electronic Information and Automation, Aba Teachers University, Pixian Street, Sichuan, 623002, China.
⁴ Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute for Advanced Materials, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China.
⁵ Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 211102, China.
⁶ Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA.

Abstract

The van der Waals (vdW) ferromagnet Fe_3-δ GeTe₂ has garnered significant research interest as a platform for skyrmionic spin configurations, that is, skyrmions and skyrmionic bubbles. However, despite extensive efforts, the origin of the Dzyaloshinskii-Moriya interaction (DMI) in Fe_3-δ GeTe₂ remains elusive, making it challenging to acquire these skyrmionic phases in a controlled manner. In this study, it is demonstrated that the Fe content in Fe_3-δ GeTe₂ has a profound effect on the crystal structure, DMI, and skyrmionic phase. For the first time, a marked increase in Fe atom displacement with decreasing Fe content is observed, transforming the original centrosymmetric crystal structure into a non-centrosymmetric symmetry, leading to a considerable DMI. Additionally, by varying the Fe content and sample thickness, a controllable transition between Néel-type skyrmions and Bloch-type skyrmionic bubbles is achieved, governed by a delicate interplay between dipole-dipole interaction and the DMI. The findings offer novel insights into the variable skyrmionic phases in Fe_3-δ GeTe₂ and provide the impetus for developing vdW ferromagnet-based spintronic devices.

Keywords: 2D ferromagnet Fe3-δGeTe2; Dzyaloshinskii-Moriya interaction; Fe atom displacement; magnetic skyrmions.

Abstract

Grants and funding