Topological materials that have certain atomic-level symmetries, including topological insulators and topological semi-metals, have elicited fascination among many Condensed Matter Scientists because of their complex electronic properties. Researchers in Japan have shown that a normal Semiconductor can be turned into a semi-metal. When illuminated with a circularly-polarized laser light, spin-dependent responses could be seen. This work was published in Physical Review B and explores the possibility of creating semi-metals with new physical properties by light control.
Plastic and metal are electrical conductors. It is possible for electrical currents to flow along the surface of the sample but not inside. The behavior is related to the electronic state. A new phase called a topological semi-metal provides a new playground for exploring the role of topology in Condensed Matter. The underlying physics of these systems is still being debated.
The dynamics of zinc arsenide were studied by researchers at the University of Tsukuba. electrons are not free to move around on their own but can be propelled by energy from an external light source, which is why zinc arsenide is considered a narrow-gap Semiconductor. The material can show a special state called a "Floquet-Weyl semi-metal" under certain conditions. Weyl fermions can be used to carry the electrical current. Weyl fermions can move quickly through the material because they travel as if they have zero mass.
The author says that Floquet-Weyl semi-metals have a number of rare properties that can be used in electronic devices. The spin-down electrons and spin-up ones form different phases when a left-handed continuous-wave laser is used. There is a semi-metal called nodal-line semi-metal nearby.
The understanding of the underlying physics of zinc arsenide can be deepened by our exploration of the Transient Dynamics of excitations. This research can help speed up the development of techniques for light- Induced Surface Magnetization.
More information: Runnan Zhang et al, Floquet-Weyl semimetals generated by an optically resonant interband transition, Physical Review B (2022). DOI: 10.1103/PhysRevB.106.085206 Journal information: Physical Review B
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