520 research outputs found
Structure determination of a brownmillerite Ca2Co2O5 thin film by Precession Electron Diffraction
Calcium cobaltite thin films with a ratio Ca/Co=1 were grown on (101)-NdGaO3
substrate by the pulsed laser deposition technique. The structure of the
deposited metastable phase is solved using a precession electron diffraction 3D
dataset recorded from a cross-sectional sample. It is shown that an ordered
oxygen-deficient Ca2Co2O5+d perovskite of the brownmillerite-type with lattice
parameters a= 0.546nm, b=1.488nm and c=0.546nm (SG: Ibm2) has been stabilized
using the substrate induced strain. The structure and microstructure of this
metastable cobaltite is further discussed and compared to related bulk
materials based on our transmission electron microscopy investigationsComment: 13 pages, 10 figures, 2 tables, accepted in Phys. Rev.
Rhodium Doped Manganites : Ferromagnetism and Metallicity
The possibility to induce ferromagnetism and insulator to metal transitions
in small A site cation manganites Ln_{1-x}Ca_xMnO_3 by rhodium doping is shown
for the first time. Colossal magnetoresistance (CMR) properties are evidenced
for a large compositional range (0.35 \leq x < 0.60). The ability of rhodium to
induce such properties is compared to the results obtained by chromium and
ruthenium doping. Models are proposed to explain this behavior.Comment: 11 pages, 8 figure
A Statistical Video Content Recognition Method Using Invariant Features on Object Trajectories
Absence of long-range Ni/Mn ordering in ferromagnetic La2NiMnO6 thin films
Epitaxial La2NiMnO6 thin films have been grown on (001)-oriented SrTiO3 using
the PLD technique. The thin films are semiconducting and FM with a TC close to
270K, a coercive field of 920Oe, and a saturation magnetization of 5muB per
f.u. TEM, conducted at RT, reveals a majority phase having "I-centered"
structure with a=c=1.4asub and b=2asub along with a minority phase-domains
having "P-type" structure (asub being the lattice parameter of the perovskite
structure). A discusion on the presence of Ni/Mn long-range ordering, in light
of recent literature on double perovskites La2NiMnO6 is presented.Comment: To be published in Applied Physics Letter
Cryogenic Design of the 43 T LNCMI Grenoble Hybrid Magnet
AbstractThe association of two inner resistive coils (Polyhelix and Bitter) producing 34.5Â T with an outer NbTi superconducting coil producing 8.5Â T to obtain a 43Â T hybrid magnet is a technical challenge. Accidental failure modes leading to complex electromagnetic behaviors and large transient dynamical forces should be anticipated. These considerations lead to a reinforced design and a thermo-hydraulic strategy to limit the overpressure. The cryostat has been designed with innovative thermo-mechanical supports sustaining the coil at 1.8Â K-1200 hPa and the eddy current shield at 30Â K, both being possibly overloaded by high dynamic forces in the worst accidental failure case
Non-linear electrical response in a charge/orbital ordered CaMnO crystal : the charge density wave analogy
Non-linear conduction in a charge-ordered manganese oxide
PrCaMnO is reported. To interpret such a feature, it is
usually proposed that a breakdown of the charge or orbitally ordered state is
induced by the current. The system behaves in such a way that the bias current
may generate metallic paths giving rise to resistivity drop. One can describe
this feature by considering the coexistence of localized and delocalized
electron states with independent paths of conduction. This situation is
reminiscent of what occurs in charge density wave systems where a similar
non-linear conduction is also observed. In the light of recent experimental
results suggesting the development of charge density waves in charge and
orbitally ordered manganese oxides, a phenomenological model for charge density
waves motion is used to describe the non-linear conduction in
PrCaMnO. In such a framework, the non-linear conduction
arises from the motion of the charge density waves condensate which carries a
net electrical current.Comment: 13 pages, 6 figure
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