Magnetism and spin-orbit coupling in Ir-based double perovskites   La$_(2-x$Sr$_x$CoIrO$_6$
  We have studied Ir spin and orbital magnetic moments in the double perovskites La$_{2-x}$Sr$_x$CoIrO$_6$ by x-ray magnetic circular dichroism. In La$_2$CoIrO$_6$, Ir$^{4+}$ couples antiferromagnetically to the weak ferromagnetic moment of the canted Co$^{2+}$ sublattice and shows an unusually large negative total magnetic moment (-0.38\,$\mu_{\text B}$/f.u.) combined with strong spin-orbit interaction. In contrast, in Sr$_2$CoIrO$_6$, Ir$^{5+}$ has a paramagnetic moment with almost no orbital contribution. A simple kinetic-energy-driven mechanism including spin-orbit coupling explains why Ir is susceptible to the induction of substantial magnetic moments in the double perovskite structure. 
A. Kolchinskaya, P. Komissinskiy, M. Baghaie Yazdi, M. Vafaee, D.   Mikhailova, N. Narayanan, H. Ehrenberg, F. Wilhelm, A. R...
cond-mat.str-el