Intrinsic anomalous Hall effect and Lifshitz transition in a ferromagnetic kagome-lattice metal

Abstract

Magnetic topological materials with broken time-reversal symmetry have demonstrated colossal intrinsic anomalous Hall effects, originating from large Berry curvature in momentum space. Here, we report the electrical transport study of a ferromagnetic kagome-lattice material Nd3Al, which is predicted to be a magnetic topological high symmetry line metal candidate. We observed a polarity reversal of ordinary Hall resistivity across 40 K, plainly indicating a perceptible shift in chemical potential and change of the Fermi surface, i.e., temperature-induced Lifshitz transition. More strikingly, as the shifting of Fermi level around the band (anti-)crossing points contributes to a considerable Berry curvature, the anomalous Hall conductivity ultimately stabilizes to a constant of approximately ∼427 [Formula: see text] cm−1 below 40 K, accompanied by a maximum anomalous Hall angle reaching 1.4%, conforming to the intrinsic dissipationless topological Berry-phase mechanism. The similar scaling behavior of anomalous Hall conductivity in Nd3Al to that of magnetic Weyl semimetal Co3Sn2S2 further signals the possible presence of nontrivial topological bands in kagome Nd3Al. In view of the kagome-lattice structure and predicted topological nature, our work unveils the significant potential of the large intrinsic anomalous Hall effect in Nd3Al for investing the interaction between ferromagnetism and topology.

Spin-reorientation driven emergent phases and unconventional magnetotransport in quasi-2D vdW ferromagnet Fe4GeTe2

“…Almost identical behavior was observed in both of the devices, D95 and D16. This indicates the change in the majority carrier from holes to electrons, possibly due to the FS reconstruction or Lifshitz-like transition occurring as a result of the SRT 41,45 , however, the actual origin is not yet known. We compare the observed behavior of R 0 for F4GT with the reported result 48 on F3GT.…”

“…The interplay between magnetic exchange and effective magnetic anisotropy is possibly the reason for this spin-reorientation 20,22,44 . The recent transport measurements indicate that the SRT may lead to Lifshitz transition in the electronic structure, and as a result, the system may exhibit unusual magnetotransport and anomalous Hall effect (AHE) 41,45 . While in the case of F4GT, an anomaly in the specific heat was seen, indicating that it is indeed a thermodynamic phase transition 22 , its consequence on electron transport is still elusive.…”

Spin-reorientation driven emergent phases and unconventional magnetotransport in quasi-2D vdW ferromagnet Fe4GeTe2

“…3(c) shows that R 0 changes sign from positive (red) to negative (blue) in the vicinity of T SR and it again becomes positive below ≈ 50 K. Almost identical behavior was observed for Dev 2 (see Supplementary Information section S3.3 for details). This indicates the change in the majority carrier from holes to electrons, possibly due to the Fermi surface reconstruction or Lifshitz-like transition occurring as a result of the SRT [41,45], however, the actual origin is not yet known. We compare the observed behavior of R 0 for F4GT with the reported result [48] of F3GT.…”

“…The interplay between magnetic exchange and effective magnetic anisotropy is possibly the reason for this spin reorientation [20,22,44]. The recent transport measurements indicate that the SRT may lead to Lifshitz transition in the electronic structure and as a result, the system may exhibit unusual magneto-transport and anomalous Hall effect [41,45]. While in the case of F4GT, an anomaly in the specific heat was seen, indicating that it is indeed a thermodynamic phase transition [22], its consequence on electron transport is still elusive.…”