Abstract-Comprehensive analysis of Terahertz frequency response of Bi2Se3 and Bi2Te3 single crystals using Terahertz time-domain spectroscopy

 

Prince Sharma, Mahesh Kumar, V.P.S. Awana, Anushree Singh, Himanshu Gohil, S.S. Prabhu, 

https://www.sciencedirect.com/science/article/abs/pii/S0921510721003159

We report the Terahertz time-domain spectroscopy (THz-TDS) dielectric response of the large single crystal of Bi2Se3 and Bi2Te3, which are grown in-house through a solid-state reaction route via the self-flux method technique. We fit the obtained experimental complex dielectric constant to the Lorentz oscillator model and obtain various resonating mode strengths in both materials. The strength of dielectric constants is an order of magnitude different while comparing the Terahertz response of both the crystals. However, the dielectric relaxation times are similar for stronger modes, depicting the similarity between the two crystals.

Abstract-Coherent control of injection currents in high-quality films of Bi2Se3

D. A. Bas, K. Vargas-Velez, S. Babakiray, T. A. Johnson, P. Borisov, T. D. Stanescu, D. Lederman, A. D. Bristow

http://arxiv.org/abs/1412.7747

(Submitted on 24 Dec 2014 (v1), last revised 28 Jan 2015 (this version, v2))

Films of the topological insulator Bi2Se3 are grown by molecular beam epitaxy with in-situ reflection high-energy electron diffraction. The films are shown to be high-quality by X-ray reflectivity and diffraction and atomic-force microscopy. Quantum interference control of photocurrents is observed by excitation with harmonically related pulses and detected by terahertz radiation. The injection current obeys the expected excitation irradiance dependence, showing linear dependence on the fundamental pulse irradiance and square-root irradiance dependence of the frequency-doubled optical pulses. The injection current also follows a sinusoidal relative-phase dependence between the two excitation pulses. These results confirm the third-order nonlinear optical origins of the coherently controlled injection current. Experiments are compared to a tight-binding band structure to illustrate the possible optical transitions that occur in creating the injection current.

Comments:	11 pages, 3 figure, journal article
Subjects:	Optics (physics.optics); Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Journal reference:	Appl. Phys. Lett. 106, 041109 (2015)
DOI:	10.1063/1.4907004
Cite as:	arXiv:1412.7747 [physics.optics]
	(or arXiv:1412.7747v2 [physics.optics] for this version)