Fig. 3: Multiferroic character of the nonlinear response.
From: General nonlinear Hall current in magnetic insulators beyond the quantum anomalous Hall effect
a In a sample with physical edges, a net polarization perpendicular to the applied field accumulates at the edge. b When the geometry is cylindrical, the application of an electric field produces a perpendicular current, thereby inducing a magnetization. Since there are no edges, no polarization can accumulate. In both scenarios, Py, M ∝ E2.
