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Using terahertz pulses to shed new light on Dirac materials (Conference Presentation)
Author(s): Rohit P. Prasankumar; Nicholas Sirica; Prashant Padmanabhan; Stephane Boubanga-Tombet; Pamela Bowlan; Dmitry Yarotski; Stuart Trugman; Jianxin Zhu; Antoinette Taylor

Paper Abstract

Ultrashort terahertz (THz) pulses are a powerful tool for both probing and controlling novel phenomena in quantum materials. This is particularly useful in Dirac materials, since these materials exhibit novel magnetic and lattice excitations that can potentially be used to control their properties. Here, the use of ultrashort THz pulses to reveal the circular photogalvanic effect in the Weyl semimetal TaAs and probe magnetoplasmon modes in graphene nanoribbons will be examined. We performed THz emission spectroscopy on the (112) and (001) surfaces of the Weyl semimetal TaAs. Our data enables us to clearly distinguish between helicity-dependent photocurrents generated within the ab-plane and polarization-independent photocurrents flowing along the non-centrosymmetric c-axis. Such findings are in excellent agreement with previous static photocurrent measurements. However, by considering both the physical constraints imposed by symmetry and the temporal dynamics intrinsic to current generation and decay, we can attribute these transient photocurrents to the underlying crystal symmetry of these materials. We also used terahertz (THz) magneto-optical spectroscopy to demonstrate how a periodic array of graphene micro-ribbons can be used to control the transmission spectrum and polarization state of a THz pulse whose electric field is oriented along the pattern’s axis of periodicity (perpendicular to the long axis of the ribbons). Our results demonstrate that graphene micro-ribbon arrays are a powerful system for controlling the coupling between light and magnetoplasmonic modes. This enables the tailoring of THz transmission profiles and polarization states using applied magnetic fields.

Paper Details

Date Published: 12 September 2019
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Proc. SPIE 11124, Terahertz Emitters, Receivers, and Applications X, 111240L (12 September 2019); doi: 10.1117/12.2529438
Show Author Affiliations
Rohit P. Prasankumar, Los Alamos National Lab. (United States)
Nicholas Sirica, Los Alamos National Lab. (United States)
Prashant Padmanabhan, Los Alamos National Lab. (United States)
Stephane Boubanga-Tombet, Los Alamos National Lab. (United States)
Pamela Bowlan, Los Alamos National Lab. (United States)
Dmitry Yarotski, Los Alamos National Lab. (United States)
Stuart Trugman, Los Alamos National Lab. (United States)
Jianxin Zhu, Los Alamos National Lab. (United States)
Antoinette Taylor, Los Alamos National Lab. (United States)


Published in SPIE Proceedings Vol. 11124:
Terahertz Emitters, Receivers, and Applications X
Manijeh Razeghi; Alexei N. Baranov; Miriam S. Vitiello, Editor(s)

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