[en] Magnetic susceptibility and specific heat measurements are presented for some Cu-containing phosphates with different copper frameworks, M₂Cu(PO₄)₂ (M=Sr and Ba: linear 1D uniform chains), BaCuP₂O₇ (double 1D uniform chains), MCuP₂O₇ (M=Ca, Sr, and Pb: zig-zag 1D uniform chains), and Sr_9.1Cu_1.4(PO₄)₇ (isolated Cu²⁺ ions). We observed short- and long-range magnetic ordering in these compounds in which the main Cu-Cu interactions are transferred through PO₄ groups. In M₂Cu(PO₄)₂ and BaCuP₂O₇, J/k_B values of about 100-140 K and k_BT_N/J<1% were obtained

[en] The effect of the La substitution for Bi in newly found triclinic perovskite BiNiO₃ was examined. The charge disproportionation of Bi ions into Bi³⁺ and Bi⁵⁺ was suppressed by 20% substitution. Bi_0.8La_0.2NiO₃ showed a metal-insulator transition at around 300 K

[en] Ln₂CuSnO₆ (Ln = Pr, Nd, and Sm) and La₂CuZrO₆ have been stabilized in the same layered double perovskite structure as La₂CuSnO₆ at high pressures of 6--8 GPa. Their crystal structures and magnetic properties were investigated. Replacement of La³⁺ by smaller lanthanide ions and Sn⁴⁺ by larger Zr⁴ increased the buckling of the Cu-O-Cu bonds in the CuO₂ layers. In Nd₂CuSnO₆, both the Cu and Nd sublattice were found to exhibit weak ferromagnetism owing to spin canting. The magnetization data showed an anomalous transition at 110 K

[en] Inelastic neutron scattering data were collected on the high pressure phase of (VO)₂P₂O₇, a S=1/2 Heisenberg antiferromagnetic alternating chain compound. The existence of a spin gap was confirmed, and the size was determined to be Δ=2.15(6) meV (=25.0(7) K). The theoretically predicted second gap (Δ'=2Δ) owing to a 2-magnon bound state was not observed. This is consistent with the high field magnetization measurement reported previously. (author)

[en] The A-site-ordered perovskites ACu₃V₄O₁₂ (A=Na⁺, Ca²⁺, and Y³⁺) have been found to be Pauli paramagnetic metals. Bond valence sum calculations, magnetic susceptibility measurement, and electronic structure calculations reveal that both Cu and V orbitals contribute to the metallic conduction. Changing the A-site ions in ACu₃V₄O₁₂ from monovalent to divalent to trivalent ions changes the physical properties in ways that in a rigid band picture can be attributed to the shift of the Fermi energy. The ACu₃V₄O₁₂ compounds, unlike the isostructural metallic CaCu₃Ru₄O₁₂, show no conclusive evidence of heavy-fermion-like behavior. (author)

[en] High-field ESR measurements were performed in Δ-chain compound [Cu(bpy)H₂O][Cu(bpy)(mal)H₂O](ClO₄)₂, which consists spin trimers with ferromagnetic and antiferromagnetic competing exchange interactions. A narrow EPR absorption line of Cu²⁺ and its anomalous temperature dependence were observed. The g-shift and frequency-dependent line width of this substance in the low-temperature region are discussed

[en] Azurite, Cu₃(OH)₂(CO₃)₂ is a candidate of the model substance for diamond chain with antiferromagnetic interaction. The millimeter and submillimeter wave ESR measurements of Cu₃(OH)₂(CO₃)₂ single crystal have been performed in the frequency region from 50 to 360 GHz and in the temperature region from 1.8 to 90 K. As the line width of ESR extends up to 3 T and it is impossible to observe by a conventional X-band ESR, the high field ESR measurement turned out to be essential. The g-shift was observed below 20 K, which corresponds to a peak of the magnetic susceptibility. Therefore, the development of the short range order may be the origin of the resonance shifts

[en] Single crystals of PrNiO₃ perovskite were grown under 4.5 GPa with NaCl and KCl flux. The electron diffraction and single crystal synchrotron X-ray diffraction experiments clearly detected the presence of a monoclinic distortion (space group P2₁/n) below the metal-insulator transition temperature T_MI, which implies the splitting of the Ni sites in the crystal in the insulating state

[en] Short communication

[en] The effect of in-plane 'trailing fields' caused by the scanning motion of a biased cantilever on ferroelectric and ferromagnetic domains of a BiFe_0.9Co_0.1O₃ thin film was investigated. BiFe_0.9Co_0.1O₃ is applicable for an ultra-low power consumption nonvolatile magnetic memory device because the magnetization is reversible by an electric field. In-plane polarization reversal was induced by the trailing field, which was approximately 1/6 of the electric field necessary for the polarization reversal using planar gap electrodes. The in-plane polarization direction of striped domain variants can be reversed by changing the slow scan direction of the cantilever keeping the bias voltage. (author)