Enhanced ultrafast relaxation rate in the Weyl semimetal phase of $\mathbf{MoT}{\mathbf{e}}_2$ measured by time-and angle-resolved photoelectron spectroscopy

Abstract

$\mathrm{MoT}{\mathrm{e}}_2$ has recently been shown to realize in its low-temperature phase the type-II Weyl semimetal (WSM). We investigated by time- and angle- resolved photoelectron spectroscopy (tr-ARPES) the possible influence of the Weyl points in the electron dynamics above the Fermi level ${\mathrm{E}}_{\mathrm{F}}$, by comparing the ultrafast response of $\mathrm{MoT}{\mathrm{e}}_2$ in the trivial and topological phases. In the low-temperature WSM phase, we report an enhanced relaxation rate of electrons optically excited to the conduction band, which we interpret as a fingerprint of the local gap closure when Weyl points form. By contrast, we find that the electron dynamics of the related compound $\mathrm{WT}{\mathrm{e}}_2$ is slower and temperature-independent, consistent with a topologically trivial nature of this material. Our results shows that tr-ARPES is sensitive to the small modifications of the unoccupied band structure accompanying the structural and topological phase transition of $\mathrm{MoT}{\mathrm{e}}_2$.

5 pages, 3 figures

References in corpus (4)

• Topological Semimetals
• Discovery of a new type of topological Weyl fermion semimetal state in Mo${}_x$W${}_{1-x}$Te${}_2$
• Raman scattering in transition metal dichalcogenides MTe2 (M = Mo, W)
• Observation of spin-polarized bands and domain-dependent Fermi arcs in polar Weyl semimetal MoTe${}_2$

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