Anomalous transport in a crystal with an intrinsic 90°-twist geometry—Co₂MnGa

We find that platelets (10 x 10 x 1 μm) cut from single crystals of the magnetic Weyl semimetal Co₂MnGa using a focused ion beam (FIB) have an intrinsic "twist." Measuring the resistance of the lamellae using the four corner contacts on the top face gives R_xx > R_yy, but measuring it using the contacts on the bottom gives R_xx < R_yy, by the same amount. The anomalous resistances appear to be confined to the surfaces, e.g., when the current is applied along an x-direction edge on the top face, the other x-direction edge on the top has an anomalously high voltage drop, but the x-direction edges on the bottom match the expected values for an isotropic slab of the same dimensions. We also observe a pattern of magnetic domains with a matching "twist." However, we find that the resistance anisotropy is unchanged by applied magnetic fields that are orders of magnitude higher than the coercive field of the material.