Eur. Phys. J. B (2018) 91: 86
https://doi.org/10.1140/epjb/e2018-80559-1

Regular Article

Signatures of bulk topology in the non-linear optical spectra of Dirac-Weyl materials

¹ Department of Physics, Indian Institute of Technology Guwahati, 781039 Guwahati, Assam, India
² Department of Physics, Manipal University, 303007 Jaipur, RJ, India
³ Indo-Korea Science and Technology Center (IKST), New Airport Road, Yelahanka, 560065 Bangalore, India
⁴ Department of Physics, Indian Institute of Technology Guwahati, 781039 Guwahati, Assam, India

^a e-mail: k.upendra@iitg.ernet.in
^b e-mail: upendraawasthi88@gmail.co

Received: 4 October 2017
Received in final form: 14 January 2018
Published online: 21 May 2018

Abstract

Graphene, topological insulators (TI) and the Weyl semimetal are shown to be well-characterized using the phenomenon of anomalous Rabi oscillation (ARO). These oscillations occur far from conventional resonance and Floquet theory shows them to be unique to these systems. Of particular interest is the bulk topological insulator (TI) where the wave-vector dependent frequency of the ARO is seen to be gapped in topologically trivial situations and gapless when there is a non-vanishing Chern number. It is shown that the Chern number may be directly inferred by performing a pump-probe experiment in the bulk without referring to surface states. A simpler alternative to the Lindblad method is invoked in order to incorporate dephasing effects that despite leading to a non-unitary time evolution of the wave-function, is nevertheless, probability conserving. The differential transmission coefficient versus the pump pulse duration (when all else is held fixed) has the form of a sinusoidal function with an amplitude that decays as a power law in the pump duration (alternatively, the “area” of the pump pulse). The exponent of this power law decay is indicative of the Chern number of the bulk in case of TI and more generally indicative of the particular member of the family of materials that may be collectively referred to as – Dirac-Weyl materials.