Direct Observation of Magnetic Bubble Lattices and Magnetoelastic Effects in van der Waals Cr2Ge2Te6

Ferromagnetic van der Waals (vdW) materials are of large current interest for the fundamental study of low-dimensional magnetism and for potential applications in multilayer heterostructures. Cr₂Ge₂Te₆ (CGT) is particularly exciting because it is a ferromagnetic semiconductor with tunable electronic and magnetic properties. Controlling the magnetic domain structure of CGT is a requirement for understanding its novel interface physics and for tuning behavior for potential devices. Herein, cryo-Lorentz transmission electron microscopy is performed in the temperature range of 12–50K to directly image the magnetic domain structures in CGT. A rich phase diagram of domain structures including stripe domains, magnetic bubble lattices of mixed-chirality, and topologically-protected lattices of homochiral magnetic bubbles is observed. The types and chiralities of the bubbles can be controlled by topographical changes in the CGT flakes. Additionally, it is observed that in-plane strain and magnetoelastic coupling can align and organize both bubble lattices and stripe domains. This study provides insights into creating and controlling complex magnetic domain structures for integration into multilayer heterostructures and for future studies of 2D magnetism.     

一步热压法制备N型Si80Ge20及其热电性能

采用一步热压法制备了N型Si80Ge20Px(x=0.2、1.0、2.0),通过改变P掺杂优化载流子浓度,对样品进行物相分析与微观结构分析,测试并比较了样品在30～800℃下的热电参数.结果表明:一步热压法可实现硅锗固相反应合金化,制备的Si80 Ge20结构致密、组分均匀;随着P掺杂增加,Si80Ge20Px的电导率...