Plateau-like magnetoresistance and topological Hall effect in Kagome magnets TbCo2 and DyCo2

Magnetoresistance (MR) and Hall resistivity of TbCo2 and DyCo2 with a Co Kagome lattice were investigated. Apart from giant negative magnetoresistance (MR) at TC, plateau-like MR and a topological Hall effect (THE) are observed at a low magnetic field for each compound below respective TC. The plateau-like MR is attributed to a compensation of negative MR with a ferromagnetically ordered structure of Tb atoms by positive MR with a noncoplanar spin structure of the Co Kagome lattice. The THE is attributed to the noncoplanar spin structure of the Co Kagome lattice only. The MR and the Hall resistivity of each compound are reduced dramatically and undergo a reversal of its sign during cooling. The reversal phenomenon at the low temperature can be related to the freezing of spins of Co atoms. The transport in DyCo2 is more sensitive to magnetic fields than that in TbCo2 which is consistent with a stronger 4 f–3 d interaction. Observations of these transport phenomena make RCo2 compounds promising for functional applications in spintronic devices.