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

Faizan Ahmad1, Rashmi Singh1, Rachana Kumar2*, Mukesh Jewariya2, 4, Chandra Shekhar3, Naresh Kumar5, Pramod Kumar1*

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

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

Abstract


The wavelength and time delay dependent reflection spectra of nano crystals Bi2Se3, 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.

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