Temperature-dependent carrier–phonon coupling in topological insulator Bi₂Se₃ Available to Purchase

Temperature-dependent (11.0 K−294.5 K) carrier–phonon coupling in Bi₂Se₃ is investigated by ultrafast pump−probe spectroscopy. The rise time of the differential reflectivity is interpreted by a combined effect of electron temperature relaxation and hot-phonon lifetime. The electron−phonon coupling constant of the bulk state (⁠$λ=0.63±0.05$⁠) is deduced from theoretical fitting. Increasing hot-phonon lifetime with decreasing temperature is attributed to a decreasing phonon−phonon collision rate. A complete analysis of the thermalization process is presented. Understanding carrier and phonon dynamics is essential for future optoelectronic and spintronic applications of topological insulators.