Primordial magnetic fields generated in the quark-hadron transition

We propose a mechanism by which magnetic fields of magnitude up to 10 ${}_{}{}^8{}_{}{}^{}$ G are generated at the quark-hadron phase transition. The primordial field is generated by currents formed at the boundaries between the quark and hadron phases, where charge separation occurs. We estimate the magnetic field generated during this phase and discuss its subsequent evolution and possible implications at later times. Today, this seed field would have an amplitude ≲${10}^{\mathrm{-}10}$ μG on scales of ∼ 1 pc in the intergalactic medium, and in the galactic interstellar medium it would correspond to ≲${10}^{\mathrm{-}5}$ μG on scales of ∼${10}^3$ AU and ≲${10}^{\mathrm{-}14}$ μG on kpc scales. The generated field may act as a seed for galactic and stellar fields.