Topological defects and topological materials

ABSTRACT

Defects in materials that interpolate between two orientation states such as domain walls and those which relate to some kind of material discontinuity, e.g. dislocations and disclinations, comprise topological defects. Noncoplanar vector arrangements, e.g. vortices, skyrmions, and possibly monopole-like excitations, also belong to this family of defects. Presence of such defects affects many of the macroscopic properties of materials, for example electronic transport and strength. Materials in which topological aspects, e.g. edge or surface states, affect the electronic, transport and other properties can be described as topological materials. Topological insulators, topological superconductors and certain Dirac materials, e.g. graphene and Weyl semimetals, belong to this class of materials. These materials possess unusual functionalities potentially useful in a variety of information processing and quantum computation based applications.

Keywords:

• Vortices
• skyrmions
• Dzyaloshinskii-Moriya interaction
• Dirac materials
• Weyl semimetals
• topological insulators

Acknowledgments

I thank Towfiq Ahmed for help with Figure 3. This work was supported by the LDRD program of the U.S. Department of Energy.