107 research outputs found
Magnetic phase diagram of cubic perovskites SrMn_1-xFe_xO_3
We combine the results of magnetic and transport measurements with Mossbauer
spectroscopy and room-temperature diffraction data to construct the magnetic
phase diagram of the new family of cubic perovskite manganites SrMn_1-xFe_xO_3.
We have found antiferromagnetic ordering for lightly and heavily Fe-substituted
material, while intermediate substitution leads to spin-glass behavior. Near
the SrMn_0.5Fe_0.5O_3 composition these two types of ordering are found to
coexist and affect one another. The spin glass behavior may be caused by
competing ferro- and antiferromagnetic interactions among Mn^4+ and observed
Fe^3+ and Fe^5+ ions.Comment: 8 pages, 10 figures, revtex, accepted to Phys. Rev.
Magnetism, Charge Order and Giant Magnetoresistance in SrFeO Single Crystals
The electronic and magnetic properties of SrFeO single crystals
with controlled oxygen content () have been studied
systematically by susceptibility, transport and spectroscopic techniques. An
intimate correlation between the spin-charge ordering and the electronic
transport behavior is found. Giant negative as well as positive
magnetoresistance are observed.Comment: published versio
Anomalous Hall Effect and Magnetoresistance of SrFe1-xCoxO3-d
Transport and magnetic studies on polycrystalline samples of SrFe1-xCoxO3-d
have been carried out to investigate the relationship between the magnetic
structure and the anomalous Hall resistivity rH. The hysteretic behavior of the
magnetization observed in the measurements with varying temperature T up and
then down after zero field cooling indicates that the system has the reentrant
spin-glass phase, which is supported by the increasing width of the magnetic
reflections observed by neutron diffraction with decreasing T below the Curie
temperature TC. Detailed analyses of the observed Hall resistivity rH indicate
that the anomalous Hall coefficient exhibits unusual behavior in the reentrant
spin-glass phase. The magnetic field (H)- and T-dependence of the
magnetoresistance of the present system can be understood by a spin dependent
tunneling model.Comment: 10 pages, 11 figures, J. Phys. Soc. Jpn. 72 (2003) No.
Non-adiabatic small polaron hopping in the n=3 Ruddlesden-Popper compound Ca4Mn3O10
Magnetotransport properties of the compound Ca4Mn3O10 are interpreted in
terms of activated hopping of small magnetic polarons in the non-adiabatic
regime. Polarons are most likely formed around Mn3+ sites created by oxygen
substoichiometry. The application of an external field reduces the size of the
magnetic contribution to the hopping barrier and thus produces an increase in
the conductivity .We argue that the change in the effective activation energy
around TN is due to the crossover to VRH conduction as antiferromagnetic order
sets in.Comment: 29 pages, 7 figure
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