Regular and irregular dynamics of spin-polarized wavepackets in a mesoscopic quantum dot at the edge of topological insulator

• Published in: Journal of experimental and theoretical physics Vol. 123; no. 6; pp. 1043 - 1059
• Main Authors: Khomitsky, D. V., Chubanov, A. A., Konakov, A. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.12.2016; Springer; Springer Nature B.V
• Subjects: CADMIUM TELLURIDES; CARRIERS; Classical and Quantum Gravitation; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DEGREES OF FREEDOM; ELECTRIC FIELDS; Electronic Properties of Solid; Electrons; Elementary Particles; ENERGY SPECTRA; IMPURITIES; MATHIEU EQUATION; Mathieu function; MERCURY TELLURIDES; Particle and Nuclear Physics; PERIODICITY; Physics; Physics and Astronomy; QUANTUM DOTS; Quantum Field Theory; QUANTUM MECHANICS; Relativity Theory; SIMULATION; Solid State Physics; SPIN ORIENTATION; TWO-DIMENSIONAL CALCULATIONS; TWO-DIMENSIONAL SYSTEMS; WAVE PACKETS
• ISSN: 1063-7761; 1090-6509
• DOI: 10.1134/S1063776116150097

The dynamics of Dirac–Weyl spin-polarized wavepackets driven by a periodic electric field is considered for the electrons in a mesoscopic quantum dot formed at the edge of the two-dimensional HgTe/CdTe topological insulator with Dirac–Weyl massless energy spectra, where the motion of carriers is less sensitive to disorder and impurity potentials. It is observed that the interplay of strongly coupled spin and charge degrees of freedom creates the regimes of irregular dynamics in both coordinate and spin channels. The border between the regular and irregular regimes determined by the strength and frequency of the driving field is found analytically within the quasiclassical approach by means of the Ince–Strutt diagram for the Mathieu equation, and is supported by full quantum-mechanical simulations of the driven dynamics. The investigation of quasienergy spectrum by Floquet approach reveals the presence of non-Poissonian level statistics, which indicates the possibility of chaotic quantum dynamics and corresponds to the areas of parameters for irregular regimes within the quasiclassical approach. We find that the influence of weak disorder leads to partial suppression of the dynamical chaos. Our findings are of interest both for progress in the fundamental field of quantum chaotic dynamics and for further experimental and technological applications of spindependent phenomena in nanostructures based on topological insulators.