Planar Hall effect in the Weyl semimetal GdPtBi

The recent discovery of Weyl and Dirac semimetals is one of the most important progresses in condensed matter physics. Among the very few available tools to characterize Weyl semimetals through electrical transport, negative magnetoresistance is most commonly used. Considering the shortcomings of this method, new tools to characterize the chiral anomaly in Weyl semimetals are desirable. We employ the planar Hall effect (PHE) as an effective technique in the half Heusler Weyl semimetal GdPtBi to study the chiral anomaly. This compound exhibits a large value of 1.5 $\mathrm{m}\mathrm{\Omega }\mathrm{cm}$ planar Hall resistivity at 2 K and in 9 T. Our analysis reveals that the observed amplitude is dominated by Berry curvature and chiral anomaly contributions. Through angle-dependent transport studies we establish that GdPtBi with relatively small orbital magnetoresistance is an ideal candidate to observe the large PHE.

Figure 1

(a) Schematic representation of the chiral charge pumping between two Weyl nodes of opposite chirality in a Weyl semimetal when the electric and magnetic fields are applied parallel to each other. (b) Experimental signature of chiral charge pumping where the quantity $\mathrm{\Delta }{\rho }_{\text{chiral}}={\rho }_0-{\rho }_{\parallel }$ shows a negative value up to 70 K in 9 T and at 2 K. The inset shows the field behavior of the $\mathrm{\Delta }{\rho }_{\parallel }$ at 2 K when measured with $\mathit{I}\parallel \mathit{B}\parallel \left[111\right]$.

Figure 2

(a) Background-subtracted periodic SdH oscillations in GdPtBi at different temperatures. (b) The Landau fan diagram showing the nontrivial $\pi$-Berry phase.

Figure 3

Schematic representations for the usual and PHE measurement geometry in the upper panels of (a) and (b), respectively. Measured usual Hall resistivity and planar Hall resistivity for GdPtBi at 9 T and 2 K in the lower panels of (a) and (b), respectively.

Figure 4

(a) Angle-dependent ${\rho }^{\text{PHE}}$ in various fields at 2 K wherein the solid lines show the fits with the modified Eq. (1). (b) Angle-dependent ${\rho }^{\text{PHE}}$ at various temperatures in 9 T. (c) Normalized fitted parameter ${\rho }_n$ and the transverse resistivity at 2 K in the left panel. The right panel shows the temperature-dependent ratio of the chiral part and the contribution of the orbital MR in the whole PHE in 9 T. (d) Angle-dependent ${\rho }_{xx}$ in various fields at 2 K wherein the solid lines show fits with Eq. (2).