Layer Hall effect without external electric field

The layer Hall effect is an intriguing phenomenon observed in magnetic topological layered materials, where the Hall response arises from the opposite deflection of electrons on top and bottom layers. To realize the layer Hall effect, space-time PT symmetry is typically broken by applying an external electric field. In this Letter, we propose a new mechanism to realize the layer Hall effect by introducing inequivalent exchange fields on both surfaces of a topological insulator thin film in the absence of an electric field. This approach yields a distinct Hall response compared to the conventional electric-field-induced layer Hall effect, particularly with respect to the Fermi level. Taking the topological insulator Sb_{2}Te_{3} as a concrete example, we demonstrate the feasibility of inducing the layer Hall effect only by coupling the top and bottom surfaces of Sb_{2}Te_{3} with different magnetic insulators. Notably, we show that both built-in electric-field-induced and inequivalent exchange-field-induced layer Hall effects can be achieved by tuning the stacking order between Sb_{2}Te_{3} and the magnetic layers. Given the well-established experimental techniques for fabricating topological insulator thin films, our work offers a viable pathway for realizing layer Hall effect without external electric field.