On T-violation signals originating from magnetic orders through double   exchange mechanism
  The photon self energy tensor in a crystal with double exchange and ferromagnetic or canting magnetic orders is analyzed at zero temperature with emphasis on the signal of the time-reversal invariance breaking. Three comparable contributions, spin susceptibility, local magnetic field and spin-orbit coupling are estimated and the prospect of their experimental detection is discussed. 
Hai-cang Ren and Maw-kuen Wu