A STUDY OF THE LA1-XYXMNSI LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.8) SOLID-SOLUTION BY MAGNETIZATION AND NEUTRON-DIFFRACTION MEASUREMENTS

Magnetization measurements and neutron diffraction study have been per formed on the CeFeSi-type La1-xYxMnSi solid solution (0 less than or e qual to x less than or equal to 0.8). The lanthanum-rich compounds (x< 0.2) are characterized by antiferromagnetic Mn (001) planes and the yt trium-rich compounds (x greater than or equal to 0.8) by ferromagnetic Mn planes. The compounds of intermediate compositions (0.4 less than or equal to x less than or equal to 0.6) order antiferromagnetically a nd display a second magnetic transition at lower temperature, yielding the formation of canted planes where both ferro- and antiferromagneti c components coexist. These magnetic behaviours are discussed and comp ared with those of isotypic ternary RMnSi and of related ThCr2Si2-type compounds. (C) 1998 Elsevier Science S.A.