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Abstract: We have carried out the de Haas–van Alphen (dHvA) experiment of an antiferromagnet under pressure. The detected dHvA branches and at ambient pressure are well explained by the corresponding dHvA branches in , indicating that the f electron is localized at ambient pressure. At 2.9GPa, where the antiferromagnetic ordering disappears completely, a new branch appears. This is approximately the same as that of 4f-itinerant Fermi surface in , suggesting that the 4f electronic state is changed into an itinerant one. [Copyright &y& Elsevier]

We present the quasi-two-dimensional Fermi surface studies in RTIn5 (R: rare earth, T: Co, Rh and Ir), together with UTGa5. The present quasi-two dimensionality is closely related to the unique crystal structure elongated along the [0 0 1] direction, which brings about a flat Brillouin zone and produces cylindrical but highly corrugated Fermi surfaces along [0 0 1]. [Copyright &y& Elsevier]

We present a new specially designed pressure cell and technique adapted for resistivity measurements in pulsed magnetic fields up to 60 T at pressures up to at least 4 GPa, and temperatures down to 1.5 K. We show that heating effects during the pulse are acceptable (less than 1 K) and can be corrected allowing reliable temperature dependences of the magnetoresistance to be obtained. We illustrate the performance with a study of the phase diagram of the heavy fermion antiferromagnet CeRH2Si2. [ABSTRACT FROM AUTHOR]

The electronic state of single crystals of CeIr2(Zn1−xCdx)20 and CePt2Cd20 has been studied by measuring the electrical resistivity ρ and specific heat C. We found that by substituting Zn with Cd, the lattice parameter expands, and the electronic specific heat coefficient γ and A coefficient, which is T2-term in ρ, are enhanced. Our experimental results reveal that the electronic state of the intermediate valence compound CeIr2Zn20 changes to a moderately heavy fermion state due to the negative chemical pressure. On the other hand, C and ρ of CePt2Cd20 show a clear jump and an abrupt change of slope below 0.3 K, respectively, due to a magnetic transition. The relation between the hybridization strength and Ce valence state has also been investigated by X-ray absorption experiment. [ABSTRACT FROM AUTHOR]

We succeeded in growing five new single crystalline compounds RPt 2 Cd 20 (R = La, Ce, Pr, Nd, and Sm) by the Cd self-flux method. These compounds are found to crystallize in the cubic CeCr 2 Al 20 -type crystal structure by the X-ray diffraction using single crystals. We measured the electrical resistivity, magnetic properties, and specific heat for all compounds. The resistivity for R = Ce, Nd, and Sm indicates an abrupt decrease, which might correspond to a magnetic transition. It is suggested that the ground state of CePt 2 Cd 20 is Γ 7 doublet from the magnetization measurement. The magnetization of PrPt 2 Cd 20 shows a metamagnetic behavior at 1.6 T in the paramagnetic state, which could be due to the crystalline electric field effect with non-Kramers Γ 3 doublet or Γ 1 singlet ground state. The contribution of optical phonon modes to the lattice specific heat is discussed in LaPt 2 Cd 20 . [ABSTRACT FROM AUTHOR]

We investigated the electronic properties of Yb 4 Ru 7 As 6 using single crystalline samples grown by the Bi-flux method. Yb 4 Ru 7 As 6 crystallizes in the cubic U 4 Re 7 Si 6 -type structure. From the electrical resistivity, magnetic susceptibility, and specific heat measurements, we have found that Yb 4 Ru 7 As 6 orders antiferromagnetically below the Néel temperature of 2.5 K with the moderately enhanced electronic specific heat coefficient of 120 mJ/(Yb-mol ⋅ K 2). A rapid increment in magnetization of about 0.25 μ B /Yb has been detected at low magnetic field below 4 K, implying a weak ferromagnetic component. • We succeeded in growing single crystals of a new Yb–Ru–As ternary compound, which is found to crystallize in the cubic U 4 Re 7 Si 6 type structure. • We investigate the physical properties of Yb 4 Ru 7 As 6. • This compound shows an antiferromagnetic transition at 2.5 K with the moderately enhanced electronic specific heat coefficient g of 120 mJ/(mol Yb K2). [ABSTRACT FROM AUTHOR]

Abstract: We have succeeded in growing a new ternary Ce compound CeAu4Si2. This compound crystallizes in the tetragonal crystal structure ( 1 1 5) with lattice parameters  Å and  Å. The local environment around Ce atoms is similar to that of the well-known ThCr2 Si2-type tetragonal structure in CeAu2 Si2. Single crystals of CeAu4Si2 were grown by the flux method using an Au4.37 Si eutectic alloy as flux. Electrical resistivity, specific heat and magnetization measurements revealed a ferromagnetic ordering at  K with a saturation moment of 1.7  /Ce. Anisotropic features in the magnetic susceptibility and magnetization were well explained by a crystalline electric field (CEF) model. Estimated excitation energies from the ground state doublet to two excited doublets are 284 and 340 K, respectively. [Copyright &y& Elsevier]

Abstract: We measured the heat capacity of CeIrSi3 (100mK

Abstract: We grew high-quality single crystals of and succeeded in observing the de Haas–van Alphen effect. The metamagnetic transition, where the antiferromagnetic state changes into the paramagnetic (field-induced ferromagnetic) state, was observed at for . On increasing the field angle , follows the dependence, indicating an Ising-type antiferromagnet. The main Fermi surface in consists of two kinds of cylindrical ones. The detected cyclotron effective mass is considerably large, ranging from to in the paramagnetic state. is a heavy-fermion compound and the 5f electrons significantly contribute to the conduction bands. [Copyright &y& Elsevier]

Abstract: We have measured the de Haas–van Alphen (dHvA) effect in under high pressures up to 3.0GPa, and found that both the dHvA frequency and cyclotron mass of -branch considerably decrease with increasing pressure. [Copyright &y& Elsevier]

Abstract: We have succeeded in growing high-quality single crystals and observing the de Haas–van Alphen (dHvA) effect in the filled skutterudite SmFe4P12. The Fermi surface topology of SmFe4P12 inferred from the dHvA experiment is similar to that of LaFe4P12, suggesting the localized character of 4f-electrons in SmFe4P12. The cyclotron effective mass enhanced to 4.3–9.2m 0 indicates strong electron correlation in this compound. [Copyright &y& Elsevier]

Abstract: CePt3Si shows an antiferromagnetic order at and enters into a heavy fermion superconducting state at . We observed the appearance of clear antiferromagnetic reflections with below . The observed antiferromagnetic peak exists even below , namely, the superconductivity coexists with antiferromagnetic order in CePt3Si. The magnetic moments of lying in the basal plane order ferromagnetically in the c-plane with inversion center, and are stacked antiferromagnetically along the c-axis with lack of inversion symmetry. Clear crystal field excitations were observed at 1 and 24meV. The magnetic susceptibility was consistent with the level scheme assuming the . [Copyright &y& Elsevier]

Abstract: The topology of the Fermi surface in CePt3Si is most likely similar to that in LaPt3Si. In fact, one small Fermi surface in CePt3Si is the same as that in LaPt3Si, where the main Fermi surface in LaPt3Si consists of three-dimensional multiply-connected Fermi surfaces. With increasing pressure, the topology of the Fermi surface in CePt3Si is approximately unchanged but the cyclotron effective mass is found to be reduced, together with a steep decrease of the Néel temperature and superconducting transition temperature. These results indicate that the heavy fermion state in CePt3Si, which is closely correlated with superconductivity, is stable at ambient pressure. [Copyright &y& Elsevier]

Abstract: We measured the magnetic susceptibility and magnetization of an antiferromagnet Ce3Sn7 with the orthorhombic crystal structure. The experimental data are found to be well explained on the basis of the crystalline electric field (CEF) 4f-scheme under the assumption that two Ce atoms in the 2(a) site possess a magnetic moment of and one Ce atom in the 4(i) site possesses no magnetic moment as in a valence fluctuating compound CeSn3, which was previously proposed by Bonnet et al. Furthermore, we carried out the de Haas–van Alphen experiment. The detected Fermi surfaces are many in number but are extremely small in volume, indicating that Ce3Sn7 is a semimetal. [Copyright &y& Elsevier]

Abstract: The metamagnetic transition was observed for -axis at at 4.2K in TmCu2 with the orthorhombic crystal structure. The magnetization for changes into after the metamagnetic transition. We confirmed by measuring the magnetostriction that the present field-induced magnetic-axis conversion is related to the quadrupole moment and induces expansion along the c-axis and shrinkage along the a-axis. [Copyright &y& Elsevier]

Abstract: We grew a single crystal of an antiferromagnetic CeRhGe and studied the electronic state by measuring the electrical resistivity, magnetic susceptibility, magnetization and neutron scattering. The magnetic susceptibility is found to be highly anisotropic, reflecting the orthorhombic crystal structure. The antiferromagnetic structure is, however, not simple, as expected from the results of the susceptibility. The resistivity peaks at the Néel temperature, which was observed under pressure, is pronounced with increasing pressure up to 1.3–1.5GPa. [Copyright &y& Elsevier]

In order to investigate the magnetic structure and Fermi surface properties of UNiGa5, we have performed elastic neutron scattering and de Haas-van Alphen(dHvA) experiments. In the neutron scattering experiment using a single crystalline sample, we determined the antiferromagnetic propagation vector Q=(1/2,1/2,1/2) in UNiGa5. In the dHvA experiment, we observed four branches. Two branches indicate cylindrical Fermi surface and the other two branches correspond to ellipsoidal ones. The cyclotron mass was not large, ranging from 1.3 to 3.1m0. [Copyright &y& Elsevier]

We report evidences for bulk nature and unconventional superconductivity in CeIn3 at P=2.65 GPa revealed by the measurements of nuclear-spin–lattice-relaxation time (T1) and ac-susceptibility (ac-χ). Both the measurements of ac-χ and T1 have pointed to a superconducting transition at T=95 mK, which is very much lower than an onset temperature Tonset=0.15 K at zero resistance. The temperature dependence of 1/T1 shows no coherence peak just below Tc, indicative of an unconventional nature for the superconductivity. [Copyright &y& Elsevier]

We performed the heat capacity, C(T), measurement under high pressure on a ferromagnetic superconductor UGe2, in order to study the pressure dependence of the anomaly in C(T) associated with the superconducting transition. A clear peak appears only around a critical pressure Pc* where an another transition temperature T* becomes 0 K. This result suggests that a bulk superconducting phase exists in the narrower pressure region around Pc* than those clarified by previous studies. [Copyright &y& Elsevier]

The angular dependence of de Haas–van Alphen effect has been measured to reveal the electronic structure of filled skutterudite PrRu4Sb12. The angular dependence of de Haas–van Alphen frequency of PrRu4Sb12 is in good agreement with that of LaRu4Sb12. Compared with PrFe4P12, no anomalous enhancement of cyclotron effective mass has been observed in this system. This change of electronic structure is attributed to the difference in the c−f hybridization strength, which is expected from the large difference in the lattice parameters. [Copyright &y& Elsevier]

We have succeeded in growing a high-quality single crystal of UIr with the monoclinic structure by the Czochralski pulling method in a tetra-arc furnace. UIr is a ferromagnetic compound. Its Curie temperature TC is 46 K and the magnetic moment is found to be oriented along the [1 0 1¯] direction by the magnetization measurement. The magnetic moment is 0.5μB/U. We have observed the de Haas-van Alphen oscillation. All the detected branches have heavy cyclotron effective masses ranging from 9.6 to 32m0. They are consistent with the electronic specific heat coefficient γ=48.5 mJ/K2 mol. [Copyright &y& Elsevier]

Abstract: We have carried out electrical resistivity experiments on the non-centrosymmetric compound CeIrGe3 under high pressures up to 24GPa. CeIrGe3 is an antiferromagnet with the Néel temperature and a successive magnetic transition at at ambient pressure. With increasing pressure, and merge around 3GPa, becomes unchanged up to 10GPa, and indicates a step-like decrease up to 20GPa. Further increasing pressure, we have found superconductivity above 20GPa with a transition temperature of 1.6K at 24GPa. The upper critical field for the magnetic field along the tetragonal [001] direction is expected to be much larger than 15T. [ABSTRACT FROM AUTHOR]

We succeeded in growing a new high quality single crystal of a ternary uranium compound UPd2Cd20. From the electrical resistivity, magnetization, magnetic susceptibility, and specific heat experiments, UPd2Cd20 is found to be an antiferromagnetic heavy-fermion compound with the Néel temperature [Formula: see text]  =  5 K and exhibits the large electronic specific heat coefficient γ exceeding 500 mJ (K(2)· mol)(-1). This compound is the first one that exhibits the magnetic ordering with the magnetic moments of the U atom in a series of UT2X20 (T: transition metal, X  =  Al, Zn, Cd). UPd2Cd20 shows typical characteristic features in heavy-fermion systems such as a broad maximum in the magnetic susceptibility at [Formula: see text] and a large coefficient A of T (2) term in the resistivity.

We have investigated quadrupole effects in tetragonal crystals of PrCu2Si2 and DyCu2Si2 by means of low-temperature ultrasonic measurements. The elastic constant C44 of PrCu2Si2 exhibits pronounced softening below 70 K down to a Néel temperature TN = 20 K, which is described in terms of a quadrupole susceptibility for a Γ5 doublet ground state and a Γ3 singlet first excited state located at 15.6 K in the crystalline electric field scheme. The C44 and C66 of DyCu2Si2 also show softening below 70 K down to TN1 = 9.7 K. A low-lying pseudo-sextet state consisting of three Kramers doublets of Γ6⊕2Γ7 brings about softening of C44 and C66 in DyCu2Si2.