497 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
Electron- and Hole-Doping Effects on -site Ordered NdBaMnO
We have investigated electron- and hole-doping effects on -site ordered
perovskite manganite NdBaMnO, which has the -type (layered)
antiferromagnetic (AFM) ground state. Electrons (holes) are introduced by
partial substitution of Ba (Nd) with Nd (Ba).
Electron-doping generates ferromagnetic (FM) clusters in the -type AFM
matrix. With increasing the electron-doping level, the volume fraction of the
FM phase or the number of the FM clusters is abruptly increasing. In contrast,
the -type AFM phase is robust against the hole-doping, and no FM correlation
is observed in the hole-doped NdBaMnO.Comment: 8 pages, 5 figures, to be published in Journal of the Physical
Society of Japa
Magnetic-field-induced switching between ferroelectric phases in orthorhombic-distortion-controlled MnO
We have investigated the dielectric and magnetic properties of
EuYMnO the presence of the 4 magnetic
moments of the rare earth ions, and have found two ferroelectric phases with
polarization along the and axes in a zero magnetic field. A magnetic
field induced switching from one to the other ferroelectric phase took plase in
which the direction of ferroelectric polarization changed from the a axis to
the c axis by the application of magnetic fields parallel to the a axis. In
contrast to the case of TbMnO, in which the 4 moments of Tb
ions play an important role in such a ferroelectric phase switching, the
magnetic-field-induced switching between ferroelectric phases in
EuYMnO does not originate from the magnetic
transition of the rare-earth 4 moments, but from that of the Mn 3 spins.Comment: 8 pages, 3 figures, RevTeX4, Proceedings of MMM 2005, to appear in J.
Appl. Phy
Gigantic magnetoelectric effect caused by magnetic-field-induced canted antiferromagnetic-paramagnetic transition in quasi-two-dimensional CaCoSiO crystal
We have investigated the magnetic and dielectric properties of
CaCoSiO crystal. The dielectricity and magnetism of
CaCoSiO are strongly coupled below a canted antiferromagnetic
transition temperature (): Magnetic fields induce electric
polarization below . Interestingly, the magnetic-field-induced
electric polarization is detected even without poling electric fields. Below
, a canted antiferromagnetic-paramagnetic transition is induced by
magnetic fields. The large magnetocapacitance is observed around .
The origin of the large magnetocapacitance is due to the magnetic-field-induced
the canted antiferromagnetic-paramagnetic transition.Comment: 3 pages, 3 figures. accepted to Applied Physics Letter
Internal magnetic field effect on magnetoelectricity in orthorhombic crystals
We have investigated the role of the 4 moment on the magnetoelectric (ME)
effect of orthorhombic MnO (=rare earth ions). In order to clarify
the role of the 4 moment, we prepared three samples: (Eu,Y)MnO without
the 4 moment, TbMnO with the anisotropic 4 moment, and
(Gd,Y)MnO with the isotropic 4 moment. The ferroelectric behaviors of
these samples are different from each other in a zero magnetic field.
(Eu,Y)MnO and (Gd,Y)MnO show the ferroelectric polarization along
the a axis in the ground state, while TbMnO shows it along the c axis.
Such difference may arise from the influence of the anisotropic Tb 4
moment. The direction of the ferroelectric polarization of MnO is
determined by the internal magnetic field arising from the 4 moment.Comment: 2 pages, 1 figure, the proceeding of International Conference of
Magnetism, to be published in the Journal of Magnetism and Magnetic Material
Pressure induced transition from a spin glass to an itinerant ferromagnet in half doped manganite Ln0.5Ba0.5MnO3 (Ln=Sm and Nd) with quenched disorder
The effect of quenched disorder on the multiphase competition has been
investigated by examining the pressure phase diagram of half doped manganite
Ln0.5B0.5MnO3 (Ln = Sm and Nd) with A-site disorders. Sm0.5Ba0.5MnO3, a spin
glass insulator at ambient pressure, switches to a ferromagnetic metal with
increasing pressure, followed by a rapid increase of the ferromagnetic
transition temperature Tc. The rapid increase of Tc was confirmed also for
Nd0.5Ba0.5MnO3. These observations indicate that the unusual suppression of the
multicritical phase boundary in the A-site disordered system, previously
observed as a function of the averaged A-site ionic radius, is essentially
controlled by the pressure and hence the band width. The effect of quenched
disorder is therefore much enhanced with approaching the multicritical region.Comment: 4 pages including 3 figure
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