Spin fluctuation induced anomalous Hall effect in the distorted kagome antiferromagnet DyAgGe

We investigate the magnetic property and charge-transport property for the kagome-frustrated antiferromagnet DyAgGe with the ZrNiAl-type crystal structure by measurements of magnetization, resistivity, and resonant x-ray scattering. The magnetization curve shows the 1/9, 1/3, 5/9, and 7/9 plateaus of saturated magnetization under the magnetic field along the $c$-axis before entering the forced ferromagnetic phase at 7.3 T and 2 K. Magnetic superlattice x-ray reflections with the modulation vector (1/3, 1/3, 0), resonantly enhanced at the Dy ${L}_{3}$ edge, are observed in these plateau phases. All of these phases, except for the 1/9-plateau phase, evolve into the paramagnetic phase around 12 to 15 K with strong competition among them in the field range of 4 to 6 T. Furthermore, we find the large negative magnetoresistivity and anomalous Hall resistivity not proportional to magnetic field or magnetization near and above the magnetic transition temperature around 3-7 T. For comparison, we also investigated the charge-transport for the isostructural magnet DyPtIn, which does not exhibit the field-induced multiple phase transitions. In contrast with the behavior of DyAgGe, DyPtIn does not show remarkable magnetoresistivity and anomalous Hall resistivity near and above the magnetic transition temperature. The anomalous Hall effect persisting above the magnetic transition temperature is likely caused by spin fluctuations enhanced by the competing multiple magnetic phases through the scalar spin chirality mechanism in DyAgGe.