Is ordering in PtNi alloys induced by spin-orbit interactions?

Abstract
Pt1-cNic alloys order at concentrations c=1/4, 1/2, 3/4 below about 900 K. This is inconsistent with all previous electronic theories which, in this case, predict segregation. The authors show that spin-orbit interactions account for this ordering tendency. The calculated order temperatures are however somewhat too low and they discuss the mechanisms that might enhance this effect.