High magnetic field pulsars and magnetars: a unified picture
  We propose a unified picture of high magnetic field radio pulsars and magnetars by arguing that they are all rotating high-field neutron stars, but have different orientations of their magnetic axes with respective to their rotation axes. In strong magnetic fields where photon splitting suppresses pair creation near the surface, the high-field pulsars can have active inner accelerators while the anomalous X-ray pulsars cannot. This can account for the very different observed emission characteristics of the anomalous X-ray pulsar 1E 2259+586 and the high field radio pulsar PSR J1814-1744. A predicted consequence of this picture is that radio pulsars having surface magnetic field greater than about $2\times 10^{14}$ G should not exist. 
Bing Zhang (1, 2), Alice K. Harding (1) ((1) Laboratory of High Energy   Astrophysics, NASA/Goddard Space Flight Center, (2)...