Quenching of Relaxation Pathway In Weyl Semimetal TaAs

Following the topological classification of materials, Weyl semimetal has been predicted theoretically and has since been experimentally confirmed. Experimental investigation on Weyl semimetal shows promise in the field of optoelectronics due to its wide spectral response from visible to near infrared regime. However, the transient dynamics of Weyl semimetal has not been clearly established. In this work, we studied the ultrafast response of tantalum arsenide (TaAs) in the optical regime through transient reflection spectroscopy with varying pump fluence. We noted two relaxation pathways for the hot injected electrons in TaAs by the pump pulse. We identified the origin of these two relaxation pathways through pump fluence dependent study. We noticed that depending on the energy of the probing wavelength, one of the relaxation pathways is quenched. The understanding of this quenching mechanism provides a reliable way to study the transient dynamics in Weyl semimetal.