Weyl Semimetals (WSM) for Electronics Applications
Abstract
Discovery of Dirac materials introduced phenomena usually regarded in the context of the high-energy physics to the everyday energy scale. The effective mass of electrons in such materials is small comparing to a typical excitation or even absent. In this case, a variety of phenomena emerges that are absent in conventional materials. Among these phenomena, the emergent conservation of helicity, the sign of the mutual orientation of the momentum of the particle and its spin, attracts a special attention. In the case of vanishing effective mass, helicity obeys a conservation law similar to the conservation law of the electric charge but independent of it. The challenge in controlling helicity is that in usual Dirac materials states with opposite helicities are difficult to distinguish. The situation drastically changed when recently materials with removed degeneracy between helicities, Weyl semimetals (WSM), were synthesized and experimentally tested. Such materials open the way to govern the density of helicity, axial charge, and its flow, axial current. The research funded by grant FA9550-16-1-0363 investigated application potential of WSM. It was shown that states with different helicities can be separated and thus the axial current can be turned into conventional electric current thus establishing axial-current conversion. Additionally, the problem of transport of Weyl fermions in structures with restricting geometry was investigated. It was found that generally in the presence of the boundary a gap in the spectrum of propagating modes opens thus making carriers massive. At the same time, this induced mass does not break the helicity conservation law. This shows that in WSM the flow of electric and axial charges can be controlled opening ways for helicity based weyltronics.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 21, 2018
- Accession Number
- AD1057741
Entities
People
- Pinaki Mazumder
Organizations
- University of Michigan