Evolution of superhigh magnetic fields of magnetars

In this paper, we consider the effect of Landau levels on the decay of superhigh magnetic fields of magnetars. Applying (3) P (2) anisotropic neutron superfluid theory yield a second-order differential equation for a superhigh magnetic field B and its evolutionary timescale t. The superhigh magnetic fields may evolve on timescales similar to(10(6)-10(7)) yrs for common magnetars. According to our model, the activity of a magnetar may originate from instability caused by the high electron Fermi energy.