Spin-lattice coupling in magnetic 2D van der Waals and topological materials

• Applicant: Dr. Laura Teresa Corredor Bohórquez
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 456950766

Low-dimensional magnetism is one of the most functional and rapidly developing area of research in theoretical and experimental physics: 2D magnets promise to be accessible, engineerable, and integrable into emergent heterostructures for previously unachieved properties and applications such as atomically thin magneto-optical and magnetoelectric devices for ultracompact spintronics, on-chip optical communications, and quantum computing. Among these materials, van der Waals magnets like the antiferromagnetic topological insulator MnBi4Te7 or the ferromagnet Cr2Ge2Te6 have in common a layered structure plus complex magnetic competing phases besides ferromagnetic or antiferromagnetic exchange interactions highly sensitive to the anisotropy, which sensitively depend on bond angles. In the case of chalcogenides like V2P2S6, Ni2P2S6 and Fe2P2S6 the presence of magnetism, strong electron correlations and Mott physics in these materials offer new avenues to explore in 2D and device physics. One of the main open questions is, given the strong sensitivity of the magnetic interactions in these materials to the structure, what is the role of magnetoelastic coupling? This is a key that could help unveiling the mechanism of the magnetism in these materials. In this project, a thorough investigation of the spin-lattice coupling in selected 2D materials through physical pressure studies (hydrostatic and uniaxial applied pressure) and dilatometry is proposed. Magnetization investigations under uniaxial pressure anticipate to be promising in giving insights on its relation with and/or control of the topological order. Furthermore, the question on the possibility of tuning the magnetic exchange via pressure will be extensively explored, as well as direct comparison of changes in the magnetic interactions induced by hydrostatic pressure with the ones induced by chemical pressure in doping experiments. Preliminary interesting results on the van-der-Waals materials alpha-RuCl3 and Cr2Ge2Te6 already show both the feasibility of dilatometry and hydrostatic pressure studies, and the richness of the information which may arise from the study of bulk single-crystal properties of 2D systems.

• DFG Programme: Research Grants