title: Nanometer size effect on structural and magnetic properties of La0.2Ca0.8MnO3.
abstract: Structural and magnetic properties of La0.2Ca0.8MnO3 nanoparticles with average size of 15-37 nm, prepared by the glycine-nitrate method, have been studied. Synchrotron experiments performed in the temperature range of 80-300 K have shown that a structural transition from room temperature orthorhombic Pnma to monoclinic P2(1)/m space group, associated with orbital ordering, occurs below 200 K in the studied particles. This transition observed for the largest particles of 37 nm is very close to that of bulk, as seen by similar temperature variation of lattice parameters and orthorhombic strain. The transition is highly suppressed for smaller 15 nm particles. Horizontal and vertical shifts of magnetic hysteresis loops (M(Shift) and H(EB)), displayed in a field cooled process, indicate size dependent exchange bias effect. It is also shown that M(shift) and H(EB), as well as the remanent magnetization M(r) and coercive field H(c) at low temperatures, exhibit a non-monotonic size dependence for particles around 23 nm. These effects may be attributed to the changes in uncompensated spins at the surface, anisotropy or alternatively to a transition from a multi-domain to the single domain state.
authors: Department of Physics, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel.
authors: V
authors: V
authors: Markovich
authors: D
authors: D
authors: Mogilyansky
authors: A
authors: A
authors: Wisniewski
authors: I
authors: I
authors: Fita
authors: R
authors: R
authors: Puzniak
authors: P
authors: P
authors: Iwanowski
authors: X D
authors: XD
authors: Wu
authors: K
authors: K
authors: Suzuki
authors: S
authors: S
authors: Chen
authors: G
authors: G
authors: Gorodetsky
mesh_terms: D002118:Calcium / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D007811:Lanthanum / Q000737:chemistry*; D060526:Magnetic Fields; D017895:Manganese Compounds / Q000737:chemistry*; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size
chemical_list: D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide; D007811:Lanthanum; D002118:Calcium