2,223 research outputs found
Reduction of critical field for magnetic and orbital-ordering phase transition in impurity-substituted NdSrMnO crystal
We have investigated the Mn-site substitution effect in
NdSrMnO single crystal, which has an -type layered
antiferromagnetic (-AFM) phase with the 3-type orbital-order.
Substitution of Fe or Ga for Mn-site suppresses both the -AFM order and
competing ferromagnetic (FM) correlation whereas Cr substitution suppresses
only the -AFM order but reactivates the underlying FM correlation via
double-exchange mechanism along the AFM coupled -direction. In
NdSrMnCrO, the -AFM state with the
orbital-order is changed into the orbital-disordered three-dimensional FM
metallic state by applying magnetic field of T, which is much
smaller than that of the parent compound NdSrMnO.Comment: 5 pages, 4 figures, to appear in APL Material
Magnetoelectric Properties of (CaSr)CoSiO Crystals
We have investigated the magnetoelectric properties of
(CaSr)CoSiO () crystals with a
quasi-two-dimensional structure. In CaCoSiO (), a canted
antiferromagnetic transition occurs at 5.6 K. The transition temperature
is increasing with increasing Sr concentration, and the rises of
the magnetization and dielectric constant become larger. Since the dielectric
constant shows large change at and the magnetocapacitance effect is
observed below , a coupling between the magnetism and dielectricity
is strong in (CaSr)CoSiO. The positive
magnetocapacitance is reduced by Sr substitution, and is not observed in . Namely, the compound of does not show the
magnetic-field-induced electric polarization. On the other hand, the negative
magnetocapacitance is enhanced by Sr substitution.Comment: 4 pages, 2figures, proceeding of International Conference on
Magnetism 200
Cr-doping effect on the orbital fluctuation of heavily doped Nd1-xSrxMnO3 (x ~ 0.625)
We have investigated the Cr-doping effect of Nd0.375Sr0.625MnO3 near the
phase boundary between the x2-y2 and 3z2-r2 orbital ordered states, where a
ferromagnetic correlation and concomitant large magnetoresistance are observed
owing to orbital fluctuation. Cr-doping steeply suppresses the ferromagnetic
correlation and magnetoresistance in Nd0.375Sr0.625Mn1-yCryO3 with 0 < y <
0.05, while they reappear in 0.05 < y < 0.10. Such a reentrant behavior implies
that a phase boundary is located at y = 0.05, or a phase crossover occurs
across y = 0.05.Comment: 3 pages, 3 figures, to be published in Journal of Applied Physic
Multiferroic properties of an \aa kermanite SrCoSiO single crystal in high magnetic fields
The magnetic and dielectric properties of \aa kermanite SrCoSiO
single crystals in high magnetic fields were investigated. We have observed
finite induced electric polarization along the c axis in high fields, wherein
all Co spins were forcibly aligned to the magnetic field direction. Existence
of the induced polarization in the spin-polarized state accompanied with the
finite slope in the magnetization curve suggests the possible role of the
orbital angular momenta in the excited states as its microscopic origin. The
emergence of the field-induced polarization without particular magnetic order
can be regarded as the magnetoelectric effects of the second order from the
symmetry point of view. A low magnetic field-driven electric polarization flip
induced by a rotating field, even at room temperature, has been successfully
demonstrated.Comment: 12 pages, 4 figure
Neutrophil Oxygen Radical Production by Dialysis Membranes
The ability of different dialysis membranes to activate polymorphonuclear neutrophil oxygen radical production was investigated with chemiluminescence. All the six membranes, namely cuprophan, cellulose acetate, polycarbonate, polysulphone, polyacrilonitrile and polymethylmethacrylate were able to interact with neutrophils and stimulate their oxygen radical production, the highest responses being seen with polyacrilonitrile, polymethylmethacrylate and polycarbonate. To analyse the role of complement in this interaction, fresh plasma, heat inactivated and zymosan-activated plasma were added: with fresh plasma oxygen radical production was stimulated on cuprophan, cellulose acetate and polysulphone, not modified on polycarbonate, and decreased on polyacrilonitrile and polymethylmethacrylate. With heat-inactivated plasma, the responses were decreased or abrogated on all the membranes except polycarbonate and polymethylmethacrylate, whereas with zymosanactivated plasma similar responses to fresh plasma were observed. In addition, when plasma was used to precoat the membrane, cuprophan, cellulose acetate and polysulphone disclosed an enhanced neutrophil oxidative burst, while precoated polyacrilonitrile and polymethylmethacrylate were less stimulatory than uncoated membranes. In contrast the precoating of polycarbonate did not modify oxygen radical production. These data suggest that neutrophil activation occurs by direct membrane neutrophil interaction. Plasmatic factors modulate this interaction but complement seems involved on cellulosic and polysulphone membranes only. Therefore, it appears that oxygen radicals produced from contact of neutrophils with the dialysis membrane might play an initial and/or additional role in the events occurring at the initiation of haemodialysi
Phase equilibrium in two orbital model under magnetic field
The phase equilibrium in manganites under magnetic field is studied using a
two orbital model, based on the equivalent chemical potential principle for the
competitive phases. We focus on the magnetic field induced melting process of
CE phase in half-doped manganites. It is predicted that the homogenous CE phase
begins to decompose into coexisting ferromagnetic phase and CE phase once the
magnetic field exceeds the threshold field. In a more quantitative way, the
volume fractions of the two competitive phases in the phase separation regime
are evaluated.Comment: 4 pages, 4 figure
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