Strange Pulsar Hypothesis
  It appears that there is a genuine shortage of radio pulsars with surface magnetic fields significantly smaller than $\sim 10^8$ Gauss. We propose that the pulsars with very low magnetic fields are actually strange stars locked in a state of minimum free energy and therefore at a limiting value of the magnetic field which can not be lowered by the system spontaneously. 
Raka Dona Ray Mandal, Monika Sinha, Manjari Bagchi, Sushan Konar, Mira   Dey and Jishnu Dey