The surprising role for phonons in Topological Semimetals*

Topological semimetals display a range of novel transport phenomena, including enormous magnetoresistance and mobilities. Observations of such behavior in topological systems suggested the quantum geometry of the electronic bands was a crucial ingredient. However similar behavior has been observed in trivial topological materials. Here I will discuss our recent experiments and first-principles calculations the provide strong evidence for the key role of phonons. In particular, we find the phonon-electron scattering far exceeds the phonon-phonon, suggesting phonons enhance the momentum of the carriers. In addition, I will outline the key ingredients in making this happen.