Kondo-like effect in the double exchange ferromagnet La0.5−xCexSr0.5MnO3

Abstract Neutron diffraction and magnetic measurements on La 0.5− x Ce x Sr 0.5 MnO 3 ( x ⩽0.4) reveal that both the Mn-moments (for all x ) and the Ce-moments ( x ⩾0.2) order ferromagnetically at different temperatures. Since Ce- and Mn-moments are coupled antiferromagnetically below T ∼100 K, they form a ferrimagnetic ground state. Further, for x =0.3 and 0.4, the temperature dependence of resistivity shows a maximum and a minimum, in contrast to a metallic behavior expected from double exchange ferromagnetism and large band width W . These results suggest an antiferromagnetic Kondo interaction between the localized Ce : 4f and polarized conduction (Mn : e g ) electrons in a ferromagnetic Kondo lattice formed by the local Mn : t 2g and itinerant e g spins.