Giant magnetostriction and spin reorientation in quaternary (Sm0.9Pr0.1)(Fe1-xCox)(2)

Unusual large magnetostrictions as well as anisotropy compensation have bee n found in quaternary Sm0.9Pr0.1(Fe1-xCox)(2). The magnetostriction constan ts lambda(111) and lambda(100) at room temperature are -4600 X 10(-6) and 5 600 X 10(-6), respectively, in Sm0.9Pr0.1(Fe0.4Co0.6)(2). The fact of \lamb da(111)\ approximate to \lambda(100)\ can be understood in terms of the com petition of different crystal distortion. The spin reorientation is also ob served, which can be understood on the basis of a two-sublattice model. A p hase diagram for the spin configurations of Sm0.9Pr0.1(Fe1-xCox)(2) (0 less than or equal to x less than or equal to 1.0) is determined by analyzing t he results of Mossbauer and magnetization measurements. The giant magnetost riction is ascribed to the combined contribution of large magnetostrictive praseodymium and of the filling of the 3d band due to the Co substitution f or Fe.