Shugo Ikeda

Fermi Surface, Magnetic and Superconducting Properties of LaRhIn5 and CeTIn5 (T: Co, Rh and Ir)

We have studied Fermi surface properties of LaRhIn 5 and CeTIn 5 (T: Co, Rh and Ir) via the de Haas–van Alphen (dHvA) experiment. The Fermi surface of a non-4 f reference compound LaRhIn 5 is quasi...

Unconventional Superconductivity in CeCoIn5 Studied by the Specific Heat and Magnetization Measurements

We measured the low-temperature specific heat in magnetic fields up to 80 kOe, together with the magnetization for the heavy-fermion superconductor CeCoIn 5 with the transition temperature T c = 2....

Novel Pressure Phase Diagram of Heavy Fermion Superconductor CePt3Si Investigated by ac Calorimetry

The pressure dependences of the antiferromagnetic and superconducting transition temperatures have been investigated by ac heat capacity measurement under high pressures for the heavy-fermion superconductor CePt 3 Si without inversion symmetry in the tetragonal structure. The Neel temperature T N = 2.2 K decreases with increasing pressure and becomes zero at the critical pressure P AF ≃0.6 GPa. On the other hand, the superconducting phase exists in a wider pressure region from ambient pressure to about 1.5 GPa. The pressure phase diagram of CePt 3 Si is thus very unique and has never been reported before for other heavy fermion superconductors.

de Haas–van Alphen Effect and Fermi Surface Properties in High-Quality Single Crystals YbCu2Si2 and YbCu2Ge2

We succeeded in growing high-quality single crystals of a valence fluctuating compound YbCu 2 Si 2 and a divalent compound YbCu 2 Ge 2 . The magnetic susceptibility of YbCu 2 Si 2 follows the Curie–Weiss law with Yb 3+ at high temperatures, but reveals a broad peak around 40 K for H ∥[100], which is due to the formation of a 4 f -itinerant heavy fermion state at lower temperatures. This is also reflected in the temperature dependence of Hall coefficient, thermoelectric power and thermal expansion. The corresponding de Haas–van Alphen (dHvA) branches are approximately explained by the 4 f -itinerant LDA band model, and the 4 f -itinerant LDA+ U model is found to be much applicable to the dHvA data. The cyclotron effective masses of main Fermi surfaces are relatively large, being 30–40 m 0 , which is consistent with the electronic specific heat coefficient γ=150 mJ/(K 2 ·mol). These results indicate that the localized 4 f electrons at high temperatures become itinerant at low temperatures, forming a narrow ...

Quasi-two Dimensional Electronic State of the Antiferromagnet UPtGa5

We have carried out the de Haas–van Alphen (dHvA) experiment to clarify the Fermi surface property of an antiferromagnet UPtGa 5 , and have constructed the magnetic phase diagram from the high-fiel...

High-Temperature Magnetic Investigations on Uranium Compounds

We investigated the magnetic property of typical uranium compounds by measuring the magnetic susceptibility in an extended temperature range up to about 800 K. The magnetic susceptibility follows the Curie–Weiss law for a localized 5 f 2 -electron compound UPd 3 and a ferromagnetic insulator UFe 4 P 12 . In most of the investigated compounds we observed a crossover effect of the 5 f electrons from a low-temperature itinerant nature to a high-temperature localized one. This is found to be characteristic for ferromagnetic superconductors such as UGe 2 and UIr, and also for antiferromagnets like USb 2 or UNiSb 2 . To assess an extension of this characteristic property in the uranium compounds we also investigated typical 5 f -itinerant compounds like UGa 3 and UPtGa 5 . The crossover effect is essentially important in heavy fermion compounds such as UPt 3 , UPd 2 Al 3 and URu 2 Si 2 . Even in the paramagnetic compound of UB 4 , the magnetic susceptibility is not temperature-independent, but approaches a 5 f ...

Magnetic and Fermi Surface Properties of UCoGa5 and URhGa5

We succeeded in growing high-quality single crystals of UCoGa5 and URhGa5 by the self-flux method and measured the electrical resistivity, magnetic susceptibility, and de Hass-van Alphen(dHvA) oscillation. Three kinds of dHvA branches were observed, ranging from 8.6x 105 to 8.1 x 106Oe, which correspond to closed Fermi surfaces. UCoGa5 and URhGas are concluded to be semimetals. The cyclotron mass is small, ranging from 0.6 m0 to 2.9 m0.

Electronic structures of layered perovskite Sr2MO4 (M=Ru, Rh, and IR)

We investigated the electronic structures of the two-dimensional layered perovskite Sr

Itinerant U 5 f band states in the layered compound UFeGa 5 observed by soft x-ray angle-resolved photoemission spectroscopy

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Electrical and Magnetic Properties of a Single Crystal UCu2Si2

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