Nonlinear properties of semiconductor superlattices in a biharmonic field

In the present work, we show that a usually unstable transparent state of a superlattice can be stabilized by a high-frequency biharmonic field with frequencies that are close, but not multiples of one another (with one of the components having sufficiently low amplitude). Furthermore, an incident biharmonic field having multiple frequencies gives rise to an absolute negative conductivity and consequent spontaneous generation of a static field in superlattices for specific phase relations of the harmonics.