  We investigate the production of the hypermagnetic gyrotropy when the
electric and magnetic gauge couplings evolve at different rates, as it happens
in the the relativistic theory of the Van der Waals forces. If a pseudo-scalar
interaction breaks the duality symmetry of the corresponding equations, the
gyrotropic configurations of the hypermagnetic fields can be amplified from the
vacuum during an inflationary stage of expansion. After charting the parameter
space of the model in terms of the rates of evolution of the magnetic and
electric gauge couplings, we identify the regions where the gyrotropy is
sufficiently intense to seed the baryon asymmetry of the Universe at the
electroweak epoch while the backreaction constraints, the strong coupling
bounds and the other astrophysical limits are concurrently satisfied.
