Dirac materials in square lattice compounds
Solid State and Surface Chemistry, Material Synthesis
Physical Chemistry of Solids and Surfaces, Material Characterisation
Final Report Abstract
In summary, during the run of this proposal we were able to expand the original results obtained on the nonsymmorphic Dirac nodal-line material ZrSiS to related materials of SG 129. We applied chemical strain to the material in ZrSiTe, lowering the nonsymmorphically protected Dirac point to the Fermi level, and explored the in uence of increased SOC and magnetism in CeSbTe. We, furthermore, put a special focus on the arising surface states in these materials. In ZrSiS, we could show that due to the broken nonsymmorphic symmetry at the surface, a topologically trivial surface state arises, which we named ‘ oating surface state’ to emphasize its strong response to the exact surface potential. In ZrSiTe, on the other hand, we encountered an additional surface state in the overlap region of the nodal line projection. This, in combination with a Berry phase shift of π when crossing this projection, allowed us to identify it as a topological drumhead surface state. So far, in the literature, there were no cases reported considering a double nodal line, which limits the drumhead surface state to the overlap region only. Besides the originally proposed materials, we also encountered several side projects. Firstly, we were able to measure CuInTe , a material interesting in photoelectrochemistry, which is usually very di cult due to the big band gaps in such materials. Secondly, we analyzed the electronic structure of LaCuSb , a candidate for a material at the interface of topology and superconductivity. Thirdly, in GdTe we studied a antiferromagnetic monolayer with high mobility. The next step in our research focuses on disordered materials, like LaZnxSb2 (where x ≈ 0.5), since not all materials of SG grow in regular single crystals. This, in combination with the introduction of a double square-net lattice in these kind of materials, would open up a new eld for extending the availability of variable parameters, while keeping the base building blocks and the resulting Dirac physics.
