  Nonlinear Landau-Zener tunneling is an important nonlinear phenomenon. We
propose to stimulate the nonlinear tunneling in a spin-orbit-coupled spinor
Bose-Einstein condensate. The system provides an experimentally tunable
nonlinearity as well as multiple avoided crossings with tunable gap size in
nonlinear dispersion relations. The nonlinearity generates tilted cusp and loop
structures around the avoided crossings, and the physical consequence of these
nonlinear structures is the nonlinear Landau-Zener tunneling. The spin-momentum
locking induced by the spin-orbit coupling leads to the time-resolved
observation of the nonlinear tunneling by measuring atom populations.
