Depinning of an anisotropic interface in random media: The tilt effect

We study the tilt dependence of the pinning-depinning transition for an interface described by the anisotropic quenched Kardar-Parisi-Zhang equation in 2+1 dimensions, where the two signs of the nonlinear terms are different from each other. When the substrate is tilted by m along the positive sign direction, the critical force F₂ (m) depends on m as F₂ (m) -F₂ (0) -|m|^1. 9 (1). The interface velocity v near the critical force follows the scaling form v|f|^_ (m^2/|f|^+) with =0. 9 (1) and =0. 2 (1), where f-F₂ (0) and F is the driving force.