Magnetic properties of low-dimensional spin systems

Magnetic Topological Materials

In recent years, the discovery of magnetic topological materials has made the interaction between magnetism and topological state a hot topic. Co₃Sn₂S₂ [1] and EuCd₂As₂ [2] are two representative magnetic topological materials and their topological states are greatly affected by the magnetic moments. Theoretical investigations pointed out that in addition to the magnitude of magnetic moments, the orientation also affects the topological state [2, 3]. Although the magnetic moments in these two materials have easy axis characteristics, their orientation can be manipulated by external magnetic field.

Optical spectroscopy can measure materials’ joint density of states [4], indirectly providing the information of band structure as well as topology. In this project, we are going to use the in-situ magnetic field to tune the magnetic moments’ orientation and simultaneously measure the optical response. Through the analysis of magneto-optical spectroscopy, we can have a deeper understanding of the interaction between magnetism and topology and important information for future applications of these materials.

References:

1. Liu, E. et al. Giant anomalous Hall effect in a ferromagnetic Kagome-lattice semimetal. Nat Phys 14, 1125-1131 (2018).
2. Ma, J. Z. et al. Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd2As2. Science advances 5, eaaw4718 (2019).
3. Akihiro Ozawa et al. Two-Orbital Effective Model for Magnetic Weyl Semimetal in Kagome-Lattice Shandite. J. Phys. Soc. Jpn. 88, 123703 (2019)
4. Dressel and G. Grüner, Electrodynamics of Solids (Cambridge University Press, Cambridge, England, 2002).