  We have analyzed the physical implications of Fermi observations of
magnetars. Observationally, no significant detection is reported in Fermi
observations of all magnetars. Then there are conflicts between outer gap model
in the case of magnetars and Fermi observations. One possible explanation is
that magnetars are wind braking instead of magnetic dipole braking. In the wind
braking scenario, magnetars are neutron stars with strong multipole field. A
strong dipole field is no longer required. A magnetism-powered pulsar wind
nebula and a braking index smaller than three are the two predictions of wind
braking of magnetars. Future deeper Fermi observations will help us make clear
whether they are wind braking or magnetic dipole braking. It will also help us
to distinguish between the magnetar model and the accretion model for AXPs and
SGRs.
