Researchers Perform In-depth Study of the Basic Properties of Topological Insulators

For over a decade, several research teams across the globe have been studying topological insulators, a relatively new class of materials. The major benefit of these materials is the existence (under specific conditions of symmetry) of dissipationless states at the sample boundary, although the bulk material retains the characteristics of an insulator. Taking these characteristics into account, researchers believe that topological insulators can be applied not only in information processing systems and advanced communications but also in quantum computing.

Spectrum of Hamiltonian (1) in zero external fields. (Image credit: Lobachevsky University)

Until now, various characteristics of topological insulators have been defined well theoretically, and certain characteristics have been experimentally verified. The fundamental characteristics that still need thorough verification are the shape of the energy dissipation curve of the edge states in a topological insulator, based on their quasimomentum components.

The law that this curve describes underlies the majority of the evident and applied characteristics of the material; hence, it is very crucial to have in-depth knowledge of its details. For instance, when the dissipation law is plotted for the electrons on the surface of the Bi2Te3 class compounds, it resembles a flower that has intricately shaped petals. Information related to the symmetry of the dissipation law, which has a direct impact on the physical characteristics of the electron gas, is contained in the shape of the petals.

Scientists at the UNN Faculty of Physics have spent many years studying the topological insulators. In the recent past, study of the effect of the dissipation law symmetry for electrons on the surface of Bi2Te3 on the observed characteristics of this material has been concluded. Denis Khomitsky, Associate Professor of the Department of Theoretical Physics, stated that scientists could demonstrate that the shape of the “petals” of the dissipation curve, or their symmetry, is a reflection of particular and measurable regularities.

These regularities are the emergence of new peaks in the absorption spectrum of electromagnetic radiation with distinctive polarization, and also qualitative differences in the dynamics of the wave packet that are evident when hexagonal corrugation or distortion of the spectrum is considered.

With the results obtained, we will be able to estimate in our future optical and transport experiments the real contribution of this corrugation, that is, to describe more accurately the details of the “petal” shape of the dissipation law.

Denis Khomitsky

The article has been published in the Journal of Experimental and Theoretical Physics in April 2018. The authors believe that a better knowledge of this law will help in speeding up the development of practically advantageous applications and devices based on this category of materials.

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