  We show that the asymmetric tunneling spectrum observed in the cuprate
superconductors stems from the existence of a competing order. The competition
between the competing order and superconductivity can create a charge depletion
region near the surface. The asymmetric response of the depletion region as the
function of the external voltage causes the asymmetric tunneling spectrum. The
effect is very general in a system which is near the phase boundary of two
competing states favoring different carrier densities. The asymmetry which has
recently been observed in the point-contact spectroscopy of the heavy fermion
superconductor CeCoIn5 is another example of this effect.
