Large anomalous Hall effect in spin fluctuating devil’s staircase

Electrons in metals can show a giant anomalous Hall effect (AHE) when interacting with
characteristic spin texture. The AHE has been discussed in terms of scalar-spin-chirality (SSC) in
long-range-ordered noncollinear spin texture typified by Skyrmion. The SSC becomes effective
even in the paramagnetic state with thermal fluctuations, but the resultant AHE has been limited
to be very small. Here, we report the observation of large AHE caused by the spin fluctuation near 25 the devil’s staircase transition in a collinear antiferromagnetic metal SrCo6O11. The AHE is
prominent near and above the transition temperature at moderate magnetic fields, where the
anomalous Hall angle becomes highest level among known oxide collinear ferromagnets/antiferromagnets (>2%). Furthermore, the anomalous Hall conductivity is
quadratically scaled to the conductivity. These results imply that the thermally induced solitonic 30
spin defects inherent to the devil’s staircase transition promote the SSC-induced skew scattering.