198 research outputs found
Magnetic studies of the lightly Ru doped perovskite rhodates Sr(Ru,Rh)O
The solid solution between the ferromagnetic metal SrRuO and the enhanced
paramagnetic metal SrRhO was recently reported [K. Yamaura et al., Phys.
Rev. B 69 (2004) 024410], and an unexpected feature was found in the specific
heat data at =0.9 of SrRuRhO. The feature was reinvestigated
further by characterizing additional samples with various Ru concentrations in
the vicinity of =0.9. Specific heat and magnetic susceptibility data
indicate that the feature reflects a peculiar magnetism of the doped
perovskite, which appears only in the very narrow composition range
0.850.95.Comment: Accepted for publication in a special issue of Physica B (the
proceedings of SCES04
Electronic properties of the novel 4d metallic oxide SrRhO3
The novel 4d perovskite compound SrRhO3 was investigated by isovalent doping
studies. The solubility limits of Ca and Ba onto Sr-site were below 80% and
20%, respectively. Although SrRhO3 was chemically compressed, approximately
5.7% by the Ca doping, no significant influence was observed on the magnetic
and electrical properties.Comment: To be published in a special issue of Physica B (the proceedings of
LT23
A new series of oxycarbonate superconductors (Cu(0.5)C(0.5))(m)Ba(m+1)Ca(n-1)Cu(n)O2(m+n)+1
We found a new series of oxycarbonate superconductors in the Ba-CaCu-C-O system under high pressure of 5 GPa. Their ideal formula is (Cu(0.5)C(0.5)(m)Ba(m+1)Ca(n-1)Cu(n)O2)((m+n)+1) ((Cu,C)-m(m+1)(n-1)n). Thus far, n = 3, 4 members of the m = 1 series, (Cu,C)-1223 and (Cu,C)-1234, have been prepared in bulk while n = 4, 5 members, (Cu,C)-2334 and (Cu,C)-2345, have been prepared for the m = 2 series. (Cu,C)-1223 shows superconductivity below 67 K while T(sub c)'s of other compounds are above 110 K. In particular, (Cu,C)-1234 has the highest T(sub c) of 117 K
Metallic conductivity and a Ca substitution study of NaRh2O4 comprising a double chain system
The metallic compound NaRh2O4 forms a full range solid solution to the
insulating phase CaRh2O4. At a Na concentration of 0.25 moles per formula unit,
we found an unexpected contribution to the specific heat at low temperature [K.
Yamaura et al. Chem. Mater. 17 (2005) 359]. To address this issue, specific
heat and ac and dc magnetic susceptibilities were additionally measured under a
variety of conditions for the Na0.25 sample. A new set of data clearly indicate
the additional specific heat is magnetic in origin; however, the magnetic
entropy is fairly small (~1 % of Schottky term for a simple splitting doublet),
and there is no other evidence to suggest that a magnetic phase transition is
responsible for the anomalous specific heat.Comment: Accepted for publication in a special issue of Physica B (the
proceedings of SCES05
Magnetic phase transitions in SmCoAsO
Magnetization, x-ray diffraction and specific-heat measurements reveal that
SmCoAsO undergoes three magnetic phase transitions. A ferromagnetic transition
attributed to the Co ions, emerges at TC=57 K with a small saturation moment of
0.15muB/Co. Reorientation of the Co moment to an antiferromagnetic state is
obtained at TN2=45 K. The relative high paramagnetic effective moment Peff=1.57
MuB/Co indicates an itinerant ferromagnetic state of the Co sublattice. The
third magnetic transition at TN1=5 K is observed clearly in the specific-heat
study only. Both magnetic and 57Fe Mossbauer studies show that substitution of
small quantities of Fe for Co was unsuccessful.Comment: 10pages text+Figures: comments welcome ([email protected]
Correlation between Tc and Lattice Parameters of Novel Superconducting NaxCoO2 yH2O
We synthesized the five batches of the samples of the novel P3 type
superconductor, Na(HO)CoOHO, by the
soft chemical process starting from -NaCoO. The chemical and
structural properties varied rather widely from batch to batch, with a result
that varied from 4.6 K to 3.2 K. The magnetic susceptibility above
shows upturn at low temperature as in the case of the P2 phase. The
seems to be well correlated to the lattice parameters.Comment: 2 pages, 2 figures, and 1 table, to be published in J. Phys. Soc.
Jpn. 73 (9) with possible minor revision
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