On the hunt for new Weyl physics in double-symmetry-breaking Weyl semimetals

Weyl semimetals can exhibit interesting phenomena, such as giant anomalous Hall effect and chiral anomaly, due to their topological properties. However, these reported phenomena may not be unique to Weyl semimetals, or may be hindered by other classical effects, and the search for new Weyl physics - new phenomena that result from the topological Weyl nodes - remains an exciting challenge. Recently, we have been working on a new class of Weyl semimetals RAlSi (R = rare-earths) that break both inversion and time-reversal symmetry, and found evidence of new Weyl physics. In CeAlSi, we observed an unconventional Hall effect, termed “loop Hall effect”, that only appears when the Fermi level is tuned to be in the proximity of the Weyl nodes. In NdAlSi, thanks to the breaking of two symmetries, Weyl-mediated Dzyaloshinskii–Moriya interactions are found to drive collective magnetism and unusual chiral components. Our results show that double-symmetry-breaking Weyl semimetals are promising platforms for finding new Weyl physics.