title: Confined spin waves reveal an assembly of nanosize domains in ferromagneticLa1-xCaxMnO3 (x=0.17,0.2).
abstract: We report a study of spin waves in ferromagnetic La1-xCaxMnO3, at concentrations x=0.17 and x=0.2 very close to the metallic transition (x=0.225). Below T(C), in the quasimetallic state (T=150 K), nearly q-independent energy levels are observed. They are characteristic of standing spin waves confined into finite-size ferromagnetic domains, defined only in the (a,b) plane for x=0.17, and in all directions for x=0.2. They allow an estimation of the domain's size, a few lattice spacings, and of the magnetic coupling constants inside the domains. These constants, anisotropic, are typical of an orbital-ordered state, allowing one to characterize the domains as "hole poor." The precursor state of the collossal magnetoresistance metallic phase appears, therefore, as an assembly of small orbital-ordered domains.
authors.affiliation: Laboratoire Léon Brillouin, CEA-CNRS, CE-Saclay, 91191 Gif sur Yvette, France.
authors.forename: M
authors.initials: M
authors.lastname: Hennion
authors.forename: F
authors.initials: F
authors.lastname: Moussa
authors.forename: P
authors.initials: P
authors.lastname: Lehouelleur
authors.forename: F
authors.initials: F
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Ivanov
authors.forename: Y M
authors.initials: YM
authors.lastname: Mukovskii
authors.forename: D
authors.initials: D
authors.lastname: Shulyatev