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NMR measurements have been performed on the ordered perovskite Sr2Cu(Re0.69Ca0.31)O6 which shows ferromagnetic (ferrimagnetic) properties below Tc∼440 K with spontaneous magnetization of about 0.25 μB per formula unit at 5 K. Two kinds of NMR lines showing large enhancement of NMR signals were observed at 5 K with H=0.5 T at the frequency range from 58 to 180 MHz, and each line was attributed to the Cu1 and Cu2 site. [Copyright &y& Elsevier]

Abstract: We have studied the crystal structure and transport properties of the new cobalt oxide (CaOH)1.14CoO2. The compound has the layer structure, which consists of CdI2-type CoO2 layers and rock-salt-type double CaOH atomic layers. The two subcells have incommensurate periodicity along the a-axis, resulting in a modulated crystal structure due to the inter-subcell interaction. The structural modulation affects carrier conduction through the potential randomness. We found that the two-dimensional (2-D) variable-range-hopping-type hole conduction is dominant at low temperature. [Copyright &y& Elsevier]

Abstract: We report the synthesis and magnetization of Sr2RuREO6 (RE/Ru-211O6) with RE=Gd and Eu. Both Gd and Eu/Ru-211O6 are formed in distorted perovskite-type single phase with monoclinic P21/n space group. Magnetization (M/T) measurements exhibited antiferromagnetic ordering of Ru moments for both Gd and Eu compounds at a T N of around 30K due to super-exchange Ru–O–O–Ru interaction. Interestingly enough, detailed M/H plots of Gd/Ru-211O6 exhibited the development of a ferromagnetic (FM) component at 20K. Furthermore, below 10K, the FM component disappears, and rather spin freezing field (H SF) of around 1000Oe is seen at 5K. In case of Eu/Ru-211O6, the basic antiferromagnetic ordering of Ru moments remains invariantly down to 5K, and the appearance of the FM component is not seen. It seems that the high magnetic moment of 8μ B for Gd3+ influences the anti ferromagnetic (AFM) ordering of Ru in case of Gd/Ru-211O6. [Copyright &y& Elsevier]

Abstract: We have studied crystal structure, ionic-model energy calculation, and electron energy-loss spectroscopy (EELS) for a new magnetic ordered-perovskite Sr2Cu(Re0.69Ca0.31)O6 in order to determine oxidation states of the Re and Cu ions. All of the experimental results of the bond-valence sum, the static energies, and the energy-loss near-edge structure (ELNES) in EEL spectra consistently indicated that the Re7+, Cu2+ and Cu3+ valence states are realized in the compound. This is evident that the Cu spins are responsible for the magnetism in the phase. By considering the Cu 3d and O 2p orbital shapes, we concluded that the unusually high Curie temperature, T C∼440K, originates in ferrimagnetism with strongly coupled Cu spins in a three dimensional (3-D) network of the Cu2+–O–Cu3+–O–Cu2+ bond in structure. [Copyright &y& Elsevier]

Abstract: The magnetic properties of solid solution Sr4− x Ba x Mn3O10 (, 1, 2, 3 and 4) were investigated. These were well characterized as two-dimensional antiferromagnets with Mn4+ (S=). The magnetic susceptibility of every sample showed a broad maximum due to short-range ordering at around 80K. The kinks in the susceptibility and peaks in the specific heat data indicated T N. The T N increased from 67 to 78K with increasing x. [Copyright &y& Elsevier]

Abstract: Magnetic properties of the calcium ferrite-type are reported. The static susceptibility data reveal a cusp at , suggesting a magnetic glassy transition. Although the crystal structure is essentially different from that of the spinel , the compound shows a similarity of the frustrated magnetism of the spinel. The probable magnetic frustration of the calcium ferrite-type compound might be due to a freezing of geometrically frustrated Mn magnetic moments in a triangular-like alignment. [Copyright &y& Elsevier]

Abstract: We report on the result of muon spin relaxation measurements in a deuterated specimen of cobalt oxyhydrate superconductor, , which exhibits a hysteresis resembling ferromagnetic order in magnetic susceptibility. While the possibility of bulk ferromagnetic order is eliminated by the absence of spontaneous muon precession signal under zero field, the spectra indicate the appearance of magnetic domains below in accordance with a hysteresis in the susceptibility. This correlation demonstrates strong coupling between the water layers and the electronic state of CoO2 layers. [Copyright &y& Elsevier]