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

Neutron diffraction and magnetic measurements on La0.5-xCexSr0.5MnO3 (x les s than or equal to 0.4) reveal that both the Mn-moments (for all x) and the Ce-moments (x greater than or equal to 0.2) order ferromagnetically at dif ferent temperatures. Since Ce- and Mn-moments are coupled antiferromagnetic ally below T similar to 100 K. they form a ferrimagnetic ground state. Furt her, 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 do uble exchange ferromagnetism and large band width IV. These results suggest an antiferromagnetic Kondo interaction between the localized Ce:4f and pol arized conduction (Mn:e(g)) electrons in a ferromagnetic Kondo lattice form ed by the local Mn:t(2g) and itinerant e(g) spins. (C) 2001 Elsevier Scienc e B.V. All rights reserved.