680 research outputs found
Novel stripe-type charge ordering in the metallic A-type antiferromagnet Pr{0.5}Sr{0.5}MnO{3}
We demonstrate that an A-type antiferromagnetic (AFM) state of
Pr{0.5}Sr{0.5}MnO{3} exhibits a novel charge ordering which governs the
transport property. This charge ordering is stripe-like, being characterized by
a wave vector q ~ (0,0,0.3) with very anisotropic correlation parallel and
perpendicular to the stripe direction. This charge ordering is specific to the
manganites with relatively wide one-electron band width (W) which often exhibit
a metallic A-type AFM state, and should be strictly distinguished from the
CE-type checkerboard-like charge ordering which is commonly observed in
manganites with narrower W such as La{1-x}Ca{x}MnO{3} and Pr{1-x}Ca{x}MnO{3}.Comment: REVTeX4, 5 pages, 4 figure
Ordering Process and Its Hole Concentration Dependence of the Stripe Order in La{2-x}Sr{x}NiO{4}
Ordering process of stripe order in La{2-x}Sr{x}NiO{4} with x being around
1/3 was investigated by neutron diffraction experiments. When the stripe order
is formed at high temperature, incommensurability \epsilon of the stripe order
has a tendency to show the value close to 1/3 for the samples with x at both
sides of 1/3. With decreasing temperature, however, \epsilon becomes close to
the value determined by the linear relation of \epsilon = n_h, where n_h is a
hole concentration. This variation of the \epsilon strongly affects the
character of the stripe order through the change of the carrier densities in
stripes and antiferromagnetic domains.Comment: 5 pages, 3 figures, REVTeX, to be published in Phys. Rev.
Orbital Ordering Structures in (Nd,Pr)0.5Sr0.5MnO3 Manganite Thin Films on Perovskite (011) Substrates
Structural study of orbital-ordered manganite thin films has been conducted
using synchrotron radiation, and a ground state electronic phase diagram is
made. The lattice parameters of four manganite thin films, Nd0.5Sr0.5MnO3
(NSMO) or Pr0.5Sr0.5MnO3 (PSMO) on (011) surfaces of SrTiO3 (STO) or
[(LaAlO3){0.3}(SrAl0.5Ta0.5O3){0.7}] (LSAT), were measured as a function of
temperature. The result shows, as expected based on previous knowledge of bulk
materials, that the films' resistivity is closely related to their structures.
Observed superlattice reflections indicate that NSMO thin films have an
antiferro-orbital-ordered phase as their low-temperature phase while PSMO film
on LSAT has a ferro-orbital-ordered phase, and that on STO has no
orbital-ordered phase. A metallic ground state was observed only in films
having a narrow region of A-site ion radius, while larger ions favor
ferro-orbital-ordered structure and smaller ions stabilize
antiferro-orbital-ordered structure. The key to the orbital-ordering transition
in (011) film is found to be the in-plane displacement along [0-1 1] direction.Comment: 19pages, 11 figure
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