Magnetic and electric properties of the metallic kagome antiferromagnet CrRhAs

Abstract

CrRhAs is an antiferromagnetic kagome metal predicted to host a nontrivial spin texture with vector spin chirality [Huang \textit{et al.}, \textit{npj Quantum Mater.} \textbf{8}, 32 (2023)]. We report the synthesis and basic characterization of CrRhAs single crystals, which exhibit an antiferromagnetic transition with $T_{\rm N}$ = 150~K, evidenced by electrical transport, heat capacity, and magnetization measurements. Hall resistivity varies linearly with magnetic field, i.e., there is no nonlinear Hall contribution. Intriguingly, the Hall coefficient changes sign between the configurations of $j \parallel ab, H \perp ab$ and $j \parallel c, H \perp c$, which is likely connected to a peculiar topology of the Fermi surface. Furthermore, for $j \parallel ab$, the Hall coefficient shows a pronounced and continuous enhancement below $T_{\rm N}$, signaling a significant reconstruction of the Fermi surface or an extra scattering from the magnons. Our results offer guidance for exploring anomalous electric transport phenomena in exotic magnetic systems.

Figures (8)

• Figure 1: (a) Crystal structure of CrRhAs. (b) Image of single crystals of CrRhAs. One grid square represents 1 mm. (c) Powder x-ray diffraction pattern of CrNiAs.
• Figure 2: Left: temperature dependence of the lattice parameters of CrRhAs. Right: a snapshot of the high-resolution XRD patterns at 50 and 250 K shows persistent hexagonal symmetry below $T_{\rm{N}}$.
• Figure 3: (a) Temperature dependence of CrRhAs resistivity, with current applied along the $c$-axis. Arrows in the inset mark the antiferromagnetic transition temperature $T_{\rm{N}}$ and the temperature of the resistivity maximum $T_{\rm{max}}$, respectively. (b) Temperature-dependent heat capacity $C(T)$ of CrRhAs. The inset shows the fit to the low-temperature data with the formula $C/T = \gamma + \beta T^2$. Temperature dependence of (c) magnetic susceptibility and (d) inverse susceptibility with magnetic field applied along the $ab$-plane and $c$-axis, respectively. The Curie-Weiss fit to the high-temperature part of the data yields the effective moment of 4.28 (4.41) $\mu_{\rm B}$ and the Curie-Weiss temperature of $-733$ K ($-759$ K) for the field applied along the $c$-axis ($ab$-plane).
• Figure 4: (a) Magnetoresistance $[\rho (H)-\rho (0)]/\rho (0)$ of CrRhAs at various temperatures. In the antiferromagnetic state (below 150 K), MR varies as $H^2$, indicated by the dashed line. (b) Temperature dependence of the magnetoresistance at 8 T, $[\rho ({\rm 8~T})-\rho (0)]/\rho (0)$.
• Figure 5: Magnetization as a function of the magnetic field applied along the (a) $ab$-plane and (b) along the $c$-axis, at various temperatures.