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

Abstract

Unusual large magnetostrictions as well as anisotropy compensation have been found in quaternary ${\mathrm{Sm}}_{0.9}{\mathrm{Pr}}_{0.1}({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{)}_{2}.$ The magnetostriction constants ${\ensuremath{\lambda}}_{111}$ and ${\ensuremath{\lambda}}_{100}$ at room temperature are $\ensuremath{-}4600\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ and $5600\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6},$ respectively, in ${\mathrm{Sm}}_{0.9}{\mathrm{Pr}}_{0.1}{(\mathrm{F}\mathrm{e}}_{0.4}{\mathrm{Co}}_{0.6}{)}_{2}.$ The fact of $|{\ensuremath{\lambda}}_{111}|\ensuremath{\approx}|{\ensuremath{\lambda}}_{100}|$ can be understood in terms of the competition of different crystal distortion. The spin reorientation is also observed, which can be understood on the basis of a two-sublattice model. A phase diagram for the spin configurations of ${\mathrm{Sm}}_{0.9}{\mathrm{Pr}}_{0.1}({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{)}_{2}$ $(0<~x<~1.0)$ is determined by analyzing the results of M\"ossbauer and magnetization measurements. The giant magnetostriction is ascribed to the combined contribution of large magnetostrictive praseodymium and of the filling of the $3d$ band due to the Co substitution for Fe.