Fig. 4.

Observation of an unusual AHE above the Lifshitz transition. (A) Antisymmetric component of the transverse resistivity vs. the magnetic field , applied at with respect to the plane of the interface. Dashed lines are guides to the eye to indicate the linear behavior at small and large fields. The low-field slope of the transverse resistance (shown by the lower dashed line in A), as a function of (red circles, Inset), is simply proportional to the component of the field out of the plane, , with a coefficient (fit shown by blue line, Inset). (B) AHE component which develops at nonzero fields vs. density and field, obtained by subtracting out the low-field normal Hall slope . (C) Derivative vs. and . The step in due to the AHE at shows up as a peak in , prominent for nearly in-plane fields () but surviving even when the field is applied out-of-plane (). The dashed line follows the evolution of this peak.