M. Hase

Antiferromagnetic long-range order caused by nonmagnetic impurities; magnetization of single-crystal Cu1−xZnxGeO3

Abstract The magnetization was obtained as a function of temperature and magnetic field of a Cu 1− x Zn x GeO 3 single-crystal with x ∼ 0.04. The temperature dependence of the magnetic susceptibility in 0.1 T parallel to the c axis shows a clear cusp around 4.5 K and decreases rapidly below 4.5 K. There is no hysteresis between the data measured in zero-field-cooling and field-cooling processes. The field dependence of the magnetization parallel to the c axis at 2.0 K exhibits an apparent increase around 1.0 T, which corresponds to a spin-flop transition. The temperature and field dependences, the anisotropy, and the absence of the hysteresis undoubtedly prove the occurrence of an antiferromagnetic long-range order below 4.5 K instead of the spin-glass-like transition reported previously. Spins below the transition temperature are ordered almost parallel to the c axis. This is the first report of magnetic long-range order caused by nonmagnetic impurities.

Effect of substitution of 3d metals for Cu in Bi2(Sr0.6Ca0.4)3Cu2Oy

Abstract The effect of the substitution of 3d metals (Fe, Co, Ni and Zn) for Cu was investigated. Lattice constants, DC resistivity, Hall effect, magnetic susceptibilities in normal and superconducting phases were measured. The change of the Hall coefficient with the substitution was much smaller than those in YBa 2 Cu 3 O y or in Y or lanthanide substituted Bi 2 (Sr, Ca) 3 Cu 2 O y . The change of T c with the substitution of Fe, Co, Ni with localized magnetic moment did not differ much from that of Zn with no magnetic moment.

TEMPERATURE DEPENDENCE OF THE SPIN-PEIERLS ENERGY GAP AND ANOMALOUS LINE SHAPES IN CUGEO3

Neutron-scattering measurements on a large single crystal of CuGeO{sub 3} have been used to determine the temperature dependence of the spin-Peierls energy gap. While the power-law behavior of the intensity of structural superlattice peaks is well fit by {ital I}({ital T}){proportional_to}({ital T}{sub {ital c}}{minus}{ital T}){sup 2{beta}} with an exponent of {beta}=0.33, the exponent for the temperature dependence of the energy gap is significantly smaller than expected for conventional spin-Peierls materials. Usual scaling relations relate the energy gap to the superlattice reflection intensity as {Delta}({ital T}){proportional_to}{ital I}{sup {ital a}} with {ital a}=1/3; the present results suggest an exponent of {ital a}{approx_equal}1/6 for CuGeO{sub 3}. An additional scattering cross section is observed in constant-{ital q} and constant-{ital E} scans creating a long tail extending to higher energies relating to a proposed scattering continuum. {copyright} {ital 1996 The American Physical Society.}

Doping effects on the anisotropic magnetic susceptibility in single-crystal La2−xSrxCuO4

Abstract The DC magnetic susceptibility of single-crystal La2−xSrxCuO4 (x = 0.08, 0.12, 0.14, 0.15, 0.19 and 0.26) was measure from 30 to 300 K under the magnetic field H = 1 T. All the samples have shown anisotropic susceptibilities, where the susceptibility with H ⊥ CuO2 plane is 1.5–3 times as large as that with H∥CuO2 plane. The doping dependence on the anisotropy is complicated, and the past explanations of the DC susceptibility do not agree with the present experimental results. The quantitative analyses of the measured data have revealed that the spin susceptibility and the temperature-independent susceptibility show different doping dependence. The doping effects of the anisotropic susceptibilities of lightly and heavily doped regions are different from each other.

Far-infrared spectroscopy in the spin-Peierls compound CuGeO 3 under high magnetic fields

Polarized far-infrared (FIR) spectroscopic measurements and FIR magneto-optical studies were performed on the inorganic spin-Peierls compound

Doping effects on the folded phonon mode in the spin-Peierls systems CuGeO3 and α′-NaV2O5

{\mathrm{CuGeO}}_{3}.

Faraday rotation and magnetization in CuGeO3 in ultra-high magnetic fields

An absorption line, which was found at

Far-infrared ESR study of cuprate compounds

98 {\mathrm{cm}}^{\ensuremath{-}1}

Raman-scattering study of CuGeO3

in the dimerized phase

Far-infrared spectroscopy in high magnetic fields

(D