Direct Observation of Magnetic Bubble Lattices and Magnetoelastic Effects in van der Waals Cr_2Ge_2Te_6

摘要

Ferromagnetic van der Waals (vdW) materials are of large current interestfor the fundamental study of low-dimensional magnetism and for potentialapplications in multilayer heterostructures. Cr_2Ge_2Te_6 (CGT) is particularlyexciting because it is a ferromagnetic semiconductor with tunable electronicand magnetic properties. Controlling the magnetic domain structure of CGTis a requirement for understanding its novel interface physics and for tuningbehavior for potential devices. Herein, cryo-Lorentz transmission electronmicroscopy is performed in the temperature range of 12–50K to directly imagethe magnetic domain structures in CGT. A rich phase diagram of domainstructures including stripe domains, magnetic bubble lattices of mixedchirality,and topologically-protected lattices of homochiral magnetic bubblesis observed. The types and chiralities of the bubbles can be controlled bytopographical changes in the CGT flakes. Additionally, it is observed that inplanestrain and magnetoelastic coupling can align and organize both bubblelattices and stripe domains. This study provides insights into creating andcontrolling complex magnetic domain structures for integration into multilayerheterostructures and for future studies of 2D magnetism.