Transient reflection spectra in topological nanocrystals of Bi2Se3, Bi2Te3, Bi2Te2Se

¹Spintronics and Magnetic Materials Laboratory: Department of Applied Sciences, IIIT-Allahabad, 211012, India

²CSIR-National Physical Laboratory: New Delhi, 110012, India

³Max Planck Institute for Chemicals Physics of Solid:  Nöthnitzer Straße, 40, 01187 Dresden, Germany

⁴Center for Quantum-Beam-based Radiation Research: Korea Atomic Energy Research Institute (KAERI), Korea

⁵Department of Physics, Motilal Nehru National Institute of Technology Allahabad 211004, India

Adv. Mater. Lett., 2017, 8 (4), pp 423-427

DOI: 10.5185/amlett.2017.6898

Publication Date (Web): Mar 14, 2017

Copyright © IAAM-VBRI Press

E-mail: pkumar@iiita.ac.in; rachanak@nplindia.org

Abstract

The wavelength and time delay dependent reflection spectra of nano crystals Bi₂Se_3, Bi­₂Te₃ and Bi­₂Te₂Se were studied for ultrafast dynamics, using pump and probe spectroscopy. We observed only one transient peak for Bi₂Se₃ below 600nm, which decreases linearly with time delay. Three transient sharp peaks were observed for Bi₂Te₃ for wavelength dependent graph, which reveals about the ultrafast dynamics of charge carrier. We also observed oscillations in Bi₂Se₃ crystal above 600 nm which was absent in Bi₂Te₃ sample.  Bi₂Te₂Se showed a single transient spectrum peak at 482 nm with the highest peak for 103ps time delay. The curve fitted Time resolve (TR) trace for both Bi₂Se₃ and Bi₂Te₃ crystals at 492 nm wavelength, revealed almost the same results for rise and decay time. 

Keywords

Ultrafast, topological, transient, spectra, femtosecond.