Direct observation of vortex decoupling in synthetic MoGe/Ge multilayers

Interlayer vortex decoupling is directly observed as a function of temperature and applied magnetic field via electronic transport perpendicular to the layers in a synthetic model system consisting of MoGe/Ge multilayers. Below the decoupling temperature ${\mathit{T}}_{\mathit{D}}$ the resistivity anisotropy collapses and striking nonlinearities appear in the perpendicular current-voltage behavior, which are not observed in parallel transport. A crossover in behavior is also observed at a field ${\mathit{H}}_{\mathit{x}}$, in accordance with theory.