Gd-5(SixGe1-x)(4): An extremum material

The large shear displacements of atomic layers in Gd-5(SixGe1-(x))(4) mater ials, coupled with the change of crystallographic symmetry and magnetic ord er, characterizes these transformations as magnetic-martensitic, which are extremely rare. The start and the end of the magnetic-martensitic transitio ns depends strongly on the direction of change (i.e., increasing or decreas ing) of either or both the temperature and magnetic field. These profound b onding, structural, electronic, and magnetic changes, which occur in the Gd -5(SixGe1-(x)) system, bring about some extreme changes of the materials' b ehavior resulting in a rich variety of unusually powerful magneto-responsiv e properties, such as the giant magnetocaloric effect, colossal magnetostri ction, and giant magnetoresistance.