Topological Hall effect enhanced at magnetic transition fields in a frustrated magnet ${\mathrm{EuCd}}_2$

Emergent magnetic fields exerted by topological spin textures of magnets lead to an additional Hall response of itinerant carriers called the topological Hall effect (THE). While THE as a bulk effect has been widely studied, THE driven by magnetic domain boundaries (DBs) has been elusive. Here, we report rich Hall responses characterized by multiple peak structures and a hysteresis loop in films of ${\mathrm{EuCd}}_2$, where Eu layers form a geometrically frustrated lattice of Heisenberg spins. We uncover a THE component sharply enhanced at magnetic transition fields, indicating a giant contribution from nontrivial spin textures possibly formed at the DBs.