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We have studied the magnetic properties of layered oxysulfide Sr[sub 2]Cu[sub 2](Co,Cu)O[sub 2]S[sub 2] with the (Co,Cu)O[sub 2] planes. Magnetic susceptibility shows a broad maximum indicative of two-dimensional antiferromagnetic nature above 140 K. Below 80 K, the divergence between zero-field cooled and field cooled magnetizations is seen; long time decay is observed at 10 and 75 K, while it is not observed at 45 K. These feature is discussed from the viewpoint of the strongly and frustrated spin system which is different from the traditional spin glass. [ABSTRACT FROM AUTHOR]

Abstract: Specific heat measurements were performed on a high-quality single crystal of . Peaks at the superconducting transition temperature and the antiferromagnetic transition temperature indicate sharp transitions compared to our previous data. The temperature dependence of specific heat below 0.3K is well described by the equation of with and , evidencing line nodes in the superconducting gap. [Copyright &y& Elsevier]

Static antiferromagnetic (AF) spin correlations of overdoped La[sub 2-x]Sr[sub x]CuO[sub 4] (LSCO) with and without Zn doping have been studied by neutron scattering. In a single crystal of Zn-free LSCO for x = 0.21, no elastic magnetic signals were observed even at 80 mK. However, elastic signals appear below 22 K in 1% Zn-doped LSCO for x = 0.21, indicating that Zn stabilizes the static AF spin correlations even in the overdoped LSCO. The present study confirmed that the AF propagation wave vector is incommensurate with the lattice, characterized as Q[sub AF] = (½ ... η ½ ± ε0) with η = 0.005(2) and ε = 0.135(2). The appearance temperature (T[sub m]) of the elastic signal degrades under higher-energy resolution, suggesting that the static correlations induced by Zn have a spinglass-like nature. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the magnetic and electronic properties of an antiferromagnet and pressure-induced superconductor CePd5Al2 by measuring the magnetization and de Haas–van Alphen effect, together with the electrical resistivity under pressure and magnetic field. Magnetic measurements including the high field magnetization at 1.3K reveal several magnetic transitions and quite complex magnetic phase diagram of this compound. Electrical resistivity measurements have been performed using diamond anvil cell up to 12GPa for the magnetic fields and [100]. The upper critical field in superconductivity is anisotropic between and [100] in the tetragonal structure, reflecting the quasi-two dimensional electronic state. [Copyright &y& Elsevier]

Abstract: The heavy fermion state in the f-electron systems is due to competition between the RKKY interaction and the Kondo effect. The typical compound is . To understand the electronic state, we studied the Fermi surface properties via the de Haas–van Alphen (dHvA) experiment and energy band calculation for , and nowadays, transuranium compounds. Pressure is also an important technique to control the electronic state. The Néel temperature decreases with increasing pressure P and becomes zero at the critical pressure for . The typical compound is an antiferromagnet , which we studied from the dHvA experiment under pressure. A change of the 4f-electronic state from localized to itinerant is realized at , revealing the first-order phase transition, together with a divergent tendency of the cyclotron mass at . It is stressed that appearance of superconductivity in is closely related to the heavy fermion state. It is also noted that the parity-mixed novel superconducting state might be realized in a pressure-induced superconductor without inversion symmetry in the crystal structure. [Copyright &y& Elsevier]

Abstract: Revolution of the pressure-induced heavy fermion state and superconductivity in an antiferromagnet CeRhIn5 have been established by high-pressure Fermi surface studies using the de Haas–van Alphen technique. A marked change of the 4f-electron nature from localized to itinerant is realized at a critical pressure under magnetic fields, together with a divergent tendency of the cyclotron mass at . The electronic state of CeIrSi3 with the non-centrosymmetric tetragonal structure is also tuned from the antiferromagnetic state to the superconducting state as a function of pressure. The upper critical field at pressure of 2.65GPa is found to be highly anisotropic: for and for , with the superconducting transition temperature . A large magnitude of and a large anisotropy of are characteristic, which reveals a new type of superconductivity closely related to the spin–orbit interaction based on the non-centrosymmetric crystal structure. [Copyright &y& Elsevier]

Abstract: We succeeded in growing single crystals of an antiferromagnet with the non-centrosymmetric orthorhombic crystal structure by the Bi-flux method. The magnetic properties were studied by measuring the magnetic susceptibility, specific heat and electrical resistivity at ambient pressure and under high pressure. The antiferromagnetic easy-axis is found to be the [010] direction (b-axis), while the other directions correspond to hard-axes in magnetization. Furthermore we studied an effect of pressure on the electronic state by measuring the electrical resistivity under pressures up to 8GPa. The Néel temperature with at ambient pressure increases slightly with increasing pressure, and then decreases rapidly above 5GPa. The Néel temperature is found to be zero around 7.2GPa. The heavy fermion state is formed in this pressure region. [Copyright &y& Elsevier]

Abstract: We report systematic high-resolution angle-resolved photoemission results on single-layered Pb-substituted Bi2Sr2CuO6+δ . We found that the intensity of shadow bands is invariable with respect to temperature and doping. This result rules out the possibility of short-range antiferromagnetic correlation and supports the structural origin of shadow bands. [Copyright &y& Elsevier]

Abstract: We succeeded in growing single crystals of (R: rare earth) and measured the magnetic susceptibility and magnetization. The lattice constants of with the tetragonal structure are well understood from a viewpoint of the lanthanide contraction, except with the divalent Yb ion. Most of compounds order antiferromagnetically. indicates two metamagnetic transitions at and below for the magnetic field along the [001] direction. The saturation moment of is in good agreement with a staggered Nd moment determined by the neutron scattering experiment. The similar metamagnetic transitions were observed in , and . [Copyright &y& Elsevier]

Abstract: We succeeded in growing a single crystal of with the orthorhombic crystal structure by the Sn-flux method and measured the electrical resistivity, magnetic susceptibility and specific heat. The magnetic easy-axis corresponds to the [001] direction, while the [100] and [010] directions are hard-axes. The crystalline electric field (CEF) scheme is proposed for . [Copyright &y& Elsevier]

Abstract: We investigated static and dynamical properties in the three-dimensional percolating Heisenberg antiferromagnets, , with the magnetic concentration close to the percolation threshold, , around the superlattice point well below . In neutron diffraction experiment, the wave number dependence of the elastic scattering component was well fitted to . Magnetic fractons were also studied using inelastic neutron scattering, and the observed fractons showed the dispersion relation of . The determined exponents, and , were in good agreement with the fractal dimension . [Copyright &y& Elsevier]

Abstract: The magnetization of single crystalline has been investigated in the antiferromagnetically ordered state up to 54T. At 4.2K, for , the magnetization shows field-induced multi-step jumps and several plateau regions above 16T, and finally reaches saturation at about 28T. The magnetization in the (001) plane, on the other hand, shows only one large jump at and 12T for and , respectively, and gradually increases toward saturation above . The magnetization curves have also been measured at higher temperatures to establish the magnetic phase diagram. [Copyright &y& Elsevier]

Abstract: We measured the electrical resistivity in antiferromagnets (a Néel temperature ) and (, ) under pressure. In , superconductivity was found in a wide pressure region from 1.8GPa to about 3.5GPa, where the superconducting transition temperature is at a critical pressure at which the Néel temperature becomes zero. On the other hand, the antiferromagnetic ordering of is stable up to 8GPa. [Copyright &y& Elsevier]

Abstract: We succeeded in growing single crystals of ternary compounds , and , and studied magnetic properties by the specific heat, magnetic susceptibility, magnetization, thermal expansion and electrical resistivity measurements. was found to be an antiferromagnet with transition temperatures and , while and have no phase transition down to , indicating a singlet ground state for both compounds. [Copyright &y& Elsevier]

The effect of magnetic field on the static and dynamic spin correlations in the noncentrosymmetric heavy-fermion superconductor CePt3Si was investigated by neutron scattering. The application of a magnetic field B increases the antiferromagnetic (AFM) peak intensity. This increase depends strongly on the field direction: for B‖[0 0 1] the intensity increases by a factor of 4.6 at a field of 6.6 T, which corresponds to more than a doubling of the AFM moment, while the moment increases by only 10% for B‖[1 0 0] at 5 T. This is in strong contrast to the inelastic response near the antiferromagnetic ordering vector, where no marked field variations are observed for B‖[0 0 1] up to 3.8 T. The results reveal that the AFM state in CePt3Si, which coexists with superconductivity, is distinctly different from other unconventional superconductors. [ABSTRACT FROM AUTHOR]