English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

It has recently been proposed that electronic band structures in crystalsgive rise to a previously overlooked type of Weyl fermion, which violatesLorentz invariance and, consequently, is forbidden in particle physics. It wasfurther predicted that Mo$_x$W$_{1-x}$Te$_2$ may realize such a Type II Weylfermion. One crucial challenge is that the Weyl points in Mo$_x$W$_{1-x}$Te$_2$are predicted to lie above the Fermi level. Here, by studying a simple modelfor a Type II Weyl cone, we clarify the importance of accessing the unoccupiedband structure to demonstrate that Mo$_x$W$_{1-x}$Te$_2$ is a Weyl semimetal.Then, we use pump-probe angle-resolved photoemission spectroscopy (pump-probeARPES) to directly observe the unoccupied band structure ofMo$_x$W$_{1-x}$Te$_2$. For the first time, we directly access states $> 0.2$ eVabove the Fermi level. By comparing our results with $\textit{ab initio}$calculations, we conclude that we directly observe the surface state containingthe topological Fermi arc. Our work opens the way to studying the unoccupiedband structure as well as the time-domain relaxation dynamics ofMo$_x$W$_{1-x}$Te$_2$ and related transition metal dichalcogenides.

Measuring Chern numbers above the Fermi level in the Type II Weyl semimetal Mo$_x$W$_{1-x}$Te$_2$