Mapping domain-wall topology in the magnetic Weyl semimetal CeAlSi

We report full vector mapping of local magnetization in CeAlSi, a Weyl semimetal in which both inversion and time-reversal symmetries are broken. The vector maps reveal unanticipated features both within domains and at their boundaries. Boundaries between domains form two kinds of walls with distinct topology and, therefore, different interactions with Weyl fermions. Domain walls aligned along the tetragonal axes, e.g., (100), exhibit emergent chirality forbidden by the bulk space group, whereas diagonal walls are nonchiral. Within the domains, we observe that the previously reported set of four easy axes aligned along the in-plane diagonals of the tetragonal structure actually split to form an octet with decreasing temperature below the magnetic transition. All the above phenomena are ultimately traced to the noncollinear magnetic structure of CeAlSi.

Automated summary

The study reports full vector mapping of local magnetization in CeAlSi, a Weyl semimetal with broken inversion and time-reversal symmetries. The vector maps reveal unexpected features within domains and at their boundaries, including two types of domain walls with distinct topology and the splitting of easy axes into an octet below the magnetic transition as temperature decreases. These phenomena are ultimately attributed to the noncollinear magnetic structure of CeAlSi.