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Abstract: We studied systematically a series of the ternary compounds (R: rare earth) which were grown in the single crystalline form by means of the flux method. Most of these compounds order antiferromagnetically at low temperatures, except for R=Y, La, Pr and Yb. The observed temperature dependence of the specific heat and the anisotropic features in the magnetic susceptibility and magnetization have been analyzed on the basis of the crystalline electric field (CEF) model, and an interesting relationship between the anisotropic exchange interaction and the CEF effect is obtained for compounds. [Copyright &y& Elsevier]

Abstract: Magnetism and superconductivity in the heavy-fermion superconductor have been studied under pressure. The antiferromagnetic and superconducting transition temperatures, and , respectively, decrease by applying pressure. becomes zero around 0.6–0.7GPa, while the pressure dependence of exhibits a shoulder-like feature around 0.7GPa, and superconductivity is found to persist in the pressure range up to about 1.5GPa. A broad peak around 5K in the temperature derivative of thermal expansion and electrical resistivity at ambient pressure begins to shift to higher temperatures above 0.7GPa. These results suggest that a critical pressure exists around 0.6–0.7GPa in . [Copyright &y& Elsevier]

Abstract: Magnetic and superconducting properties have been investigated on a single crystal of CePt3Si which is the recently discovered heavy-fermion superconductor. The effect of magnetic field on the antiferromagnetic transition temperature was studied by the iso-field thermal expansion coefficient. From these results, together with the results of the electrical resistivity under magnetic fields, magnetostriction and magnetization measurements, we have constructed the magnetic and superconducting phase diagrams for and [001]. [Copyright &y& Elsevier]

Magnetic properties in Na0.75CoO2 (space group P63/mmc) are investigated by DC magnetic measurements from 2 to 300 K. The temperature-dependent magnetic susceptibility data show Curie–Weiss behaviour down to 15 K. Spin glass like characteristics are also found; the cusp anomaly seen at 3 K, irreverisbility between zero-field and field cooled magnetic susceptibility below 13 K. [Copyright &y& Elsevier]

Magnetic and electronic nature have been investigated for the novel layered oxysulfide Sr2Cu2CoO2S2 (space group I/4mmm). Sr2Cu2CoO2S2 is the antiferromagnet with TN (=200 K) determined by the measurements of neutron powder diffraction and magnetic susceptibility (χ). The χ shows a broad maximum indicative of two-dimensional antiferromagnetic nature, which is not originated from the (Cu+S)2 layers but the strongly correlated Co2+O2 square-planes revealed by the X-ray photoemission spectroscopy. [Copyright &y& Elsevier]

EuCo 2 Ge 2 with the tetragonal structure is a Eu-divalent antiferromagnet with the Néel temperature T N = 23 K. The magnetic easy-axis corresponds to the [100] direction ( a -axis), while the [001] direction ( c -axis) is a hard-axis. The magnetization for H ∥ [ 100 ] indicates a metamagnetic transition at 25 kOe and saturates above 75 kOe. On the other hand, the hard-axis magnetization increases approximately linearly and saturates above 110 kOe. The magnetic phase diagram was constructed. A characteristic feature in EuCo 2 Ge 2 is known as a valence transition under pressure, from Eu 2 + δ to Eu 3 − δ ′ ( δ , δ ′ < 1 ). We also clarified the valence transition by measuring the electrical resistivity under pressure. The valence transition occurs at 3 GPa, with a hysteresis, and terminates at about 4.5 GPa. Further increasing pressure, the electronic state is changed into a moderate heavy fermion state and approaches the nearly trivalent electronic state. [ABSTRACT FROM AUTHOR]

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 CeCu6. To understand the electronic state, we studied the Fermi surface properties via the de Haas-van Alphen (dHvA) experiments and energy band calculations for CeSn3, CeRu2Si2, UPt3, and nowadays, transuranium compounds of NpGe3 and PuIn3, together with YbCu2Si2. Pressure is also an important technique to control the electronic state. For example, the Néel temperature decreases with increasing pressure P and becomes zero at the critical pressure for . The typical compound is an antiferromagnet CeRhIn5, 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 P c. It is stressed that appearance of superconductivity in CeRhIn5 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 CeIrSi3 without inversion symmetry in the crystal structure. [Copyright &y& Elsevier]

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: 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: High-field magnetization measurements of ( and Ge) and were carried out up to 50T. The magnetization of at 1.3K increases linearly, with a small metamagnetic transition at 7.8 and 10.5T for H//[110] and [100], respectively, and saturates at 27T for H//[100] and [110], while the magnetization also saturates at 15.5T for H//[001], without the metamagnetic transition. The high-field magnetization of at 1.3K shows no metamagnetic transition. [Copyright &y& Elsevier]

Soft X-ray absorption (XAS) spectra and their magnetic circular dichroism (MCD) have been studied at the transition-metal L2,3 thresholds of Heusler-type Fe2-xV1+xAl intermetallic compounds. Satellite structures 5 eV above the main Fe and V L2,3 XAS peaks are attributed to a singularity in the density of states, and fine structures in the V L2,3 spectra is ascribed to the multiplets. Observed MCD intensity changes as the bulk magnetization on changing the content x in Fe2-xV1+xAl. Although the observed MCD signals are small, they definitely indicate the anti-ferromagnetic coupling between the Fe and V magnetic moments, as predicted for the magnetic cluster formed around the anti-site defects in the Heusler lattice. The existence of the magnetic cluster may cause the unusual transport properties at low temperatures. [Copyright &y& Elsevier]

Abstract: We have succeeded in growing single crystals of , which crystallizes in the orthorhombic crystal structure, by the flux method and studied the anisotropic physical properties by measuring the electrical resistivity, magnetic susceptibility and specific heat. The results of these measurements indicate that undergoes two antiferromagnetic transitions at and . The electrical resistivity and susceptibility measurements reveal strong anisotropic magnetic properties. From the specific heat measurement the electronic specific heat coefficient was found to be mol. [Copyright &y& Elsevier]

Abstract: We have determined the pressure-temperature phase diagram of heavy-fermion superconductor by the AC heat capacity measurement. The Néel temperature decreases with increasing pressure and becomes zero at the critical pressure . On the other hand, the superconducting phase exists in a wider pressure region from ambient pressure to about 1.5GPa. The phase diagram of is thus very unique and has never been reported before for other heavy fermion superconductors. [Copyright &y& Elsevier]