  CP violation and the violation of baryon-minus-lepton number B-L do not
necessarily have to occur simultaneously in order to accomplish successful
leptogenesis. Instead, it suffices if new CP-violating interactions at high
energies result in primordial charge asymmetries, which are then reprocessed
into a nonvanishing B-L asymmetry by right-handed neutrinos (RHNs) at lower
energies. In this paper, we study this novel mechanism known as "wash-in
leptogenesis", utilizing axion inflation as the source of high-scale CP
violation. We specifically consider axion inflation coupled to the Standard
Model hypercharge sector, which results in the dual production of hypermagnetic
helicity and fermionic charge asymmetries. Although the survival of these
charges is endangered by sphaleron processes, magnetic diffusion, and the
chiral plasma instability, we find a large range of viable scenarios. We
consistently account for RHN flavor effects and coherence among the Standard
Model lepton flavors across a wide range of RHN masses. We find a lower bound
of 10^(5...9) GeV on the mass of the lightest RHN involved in wash-in
leptogenesis, depending on the onset of turbulence in the chiral plasma and the
Hubble scale of inflation. Our model is representative of a broader class of
new leptogenesis scenarios and suggests interesting observational signatures
with regard to intergalactic magnetic fields, primordial black holes, and
gravitational waves.
