Microscopic mechanism of the giant magnetocaloric effect in MnCoGe   alloys probed by XMCD
  One important aspect of the magneto-structural transition in MnCoGe and related materials is the reduction in saturation magnetization from the orthorhombic to the hexagonal phase. Here, by combining an element specific magnetization probe such as x-ray magnetic circular dichroism and band structure calculations, we show that the magnetic moment instability between orthorhombic and hexagonal structures originates from a reduction in the Mn sub-lattice magnetization. The consequences of the moment instability for the magnetocaloric effect are discussed. 
F. Guillou, F. Wilhelm, O. Tegus, and A. Rogalev
cond-mat.str-el