Connecting Higher-Order Topology with the Orbital Hall Effect in Monolayers of Transition Metal Dichalcogenides

Author(s)

Costa, Marcio ; Focassio, Bruno ; Canonico, Luis M. ; Cysne, Tarik P. ; Schleder, Gabriel R. ; Muniz, R. B. ; Fazzio, Adalberto ; Rappoport, Tatiana G.

• Document type: Journal article
• Source: Physical Review Letters; v. 130, n. 11, p. 7-pg., 2023-03-17.

Abstract

Monolayers of transition metal dichalcogenides (TMDs) in the 2H structural phase have been recently classified as higher-order topological insulators (HOTIs), protected by C-3 rotation symmetry. In addition, theoretical calculations show an orbital Hall plateau in the insulating gap of TMDs, characterized by an orbital Chern number. We explore the correlation between these two phenomena in TMD monolayers in two structural phases: the noncentrosymmetric 2H and the centrosymmetric 1T. Using density functional theory, we confirm the characteristics of 2H TMDs and reveal that 1T TMDs are identified by a Z(4) topological invariant. As a result, when cut along appropriate directions, they host conducting edge states, which cross their bulk energy-band gaps and can transport orbital angular momentum. Our linear response calculations thus indicate that the HOTI phase is accompanied by an orbital Hall effect. Using general symmetry arguments, we establish a connection between the two phenomena with potential implications for orbitronics and spin orbitronics. (AU)

• FAPESP's process: 19/04527-0 - Interface between crystalline topological insulators and 2D-trivial materials: defect proximity study
• Grantee: Bruno Focassio
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 17/02317-2 - Interfaces in materials: electronic, magnetic, structural and transport properties
• Grantee: Adalberto Fazzio
• Support Opportunities: Research Projects - Thematic Grants