  High-field magnetic white dwarfs have been long suspected to be the result of
stellar mergers. However, the nature of the coalescing stars and the precise
mechanism that produces the magnetic field are still unknown. Here we show that
the hot, convective, differentially rotating corona present in the outer layers
of the remnant of the merger of two degenerate cores is able to produce
magnetic fields of the required strength that do not decay for long timescales.
We also show, using an state-of-the-art Monte Carlo simulator, that the
expected number of high-field magnetic white dwarfs produced in this way is
consistent with that found in the Solar neighborhood.
