Abstract
Recent reports of a large anomalous Hall effect (AHE) in ferromagnetic Weyl semimetals (FM WSMs) have led to a resurgence of interest in this enigmatic phenomenon. However, due to a lack of tunable materials, the interplay between the intrinsic mechanism caused by Berry curvature and extrinsic mechanisms due to scattering remains unclear in FM WSMs. In this contribution, we present a thorough investigation of both the extrinsic and intrinsic AHEs in a new family of FM WSMs, PrAlGe1−xSix, where x can be tuned continuously. Based on the first-principles calculations, we show that the two end members, PrAlGe and PrAlSi, have different Fermi surfaces, but similar Weyl node structures. Experimentally, we observe moderate changes in the anomalous Hall coefficient (RS), but significant changes in the ordinary Hall coefficient (R0) in PrAlGe1−xSix as a function of x. By comparing the magnitude of R0 and RS, we identify two regimes: |R0| < |RS| for x ≤ 0.5 and |R0| > |RS| for x > 0.5. Through a detailed scaling analysis, we uncover a universal anomalous Hall conductivity (AHC) from intrinsic contribution when x ≤ 0.5. Such a universal AHC is absent for x > 0.5. Our study, thus, reveals the significance of extrinsic mechanisms in FM WSMs and reports the first observation of the transition from the intrinsic to extrinsic AHE in PrAlGe1−xSix.
Highlights
The Hall effect in ferromagnets is commonly characterized by the following empirical formula for the Hall resistivity ρxy:1,2 ρxy = ρOxy + ρAxy = R0Hz + RsMz, (1)where R0 and Rs are ordinary and anomalous Hall coefficients, respectively
The intrinsic mechanism is gaining increasing attention because it is applicable to the anomalous Hall effect (AHE) in Weyl semimetals (WSMs) where the Weyl nodes, monopoles of the Berry curvature, can potentially generate a large AHE.9
This is precisely the subject of the present article where we explored this possibility in the ferromagnetic Weyl semimetals (FM WSMs) PrAlGe1−xSix
Summary
Several WSMs have been found to exhibit such a large AHE, including pyrochlore iridates (Nd2Ir2O7), Heusler and half-Heusler compounds (Co2MnGa and GdPtBi), and ferromagnetic (FM) WSMs, such as shandite structures (Co3Sn2S2).15 All these discoveries have been interpreted as an intrinsic AHE, and the extrinsic contributions have been overlooked. One experimental approach to address this issue would be to maintain the structure of the Weyl nodes but change the Fermi surface (or vice versa) across a series of compositions and tune the relative magnitude of extrinsic and intrinsic AHE contributions This is precisely the subject of the present article where we explored this possibility in the FM WSMs PrAlGe1−xSix. We study the AHE in PrAlGe1−xSix alloys with x = 0, 0.25, 0.5, 0.7, 0.85, and 1 to investigate both intrinsic and extrinsic contributions to the AHE in this tunable FM WSM family. We reveal a transition from intrinsic to extrinsic AHEs in the same family of FM WSMs and show the possibility of tuning AHE in topological semimetals
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
