N. Wada

Magnetic and transport properties of RE3Ir4Sn13

The magnetic transport and thermal properties of RE3Ir4Sn13 (RE: La, Ce, Pr, Nd, Sm, Eu) (single crystals) have been investigated. Ce3Ir4Sn13 is found to be a heavy fermion compound with two-stage phase transitions at 0.6 K and 2.1 K. Eu3Ir4Sn13 is an intermediate valence compound with an antiferromagnetic transition at 10 K and an additional phase transition near 50 K. Sm3Ir4Sn13 has a stable Sm3+ valency, and shows an antiferromagnetic phase transition below 5.8 K. The Pr and Nd compounds show no clear magnetic phase transition down to 1.8 K.

Two magnetic transitions in Ce3Ir4Sn13

The specific heats of Ce3Ir4Sn13 have been measured between 30 mK and 70 K in magnetic fields up to 4 T. We observed the two main specific heat peaks at 0.6 K and at 2.1 K, which is resolved well into two successive peaks. A magnetic field versus temperature phase diagram is presented.

Magnetic field effects in the Kondo compounds CeCu2

The specific heat of the heavy-fermion compound CeCu 2 has been measured between 0.05 and 10 K in magnetic fields up to 60 kOe. We have found that the magnetic field above 20 kOe destroys the antiferromagnetic order and produces different types of magnetically ordered states.

Crystal structures and magnetic properties of (pyridinium nitronyl nitroxide)-X-: possible spin-1 Kagome antiferromagnet

Abstract Crystal structures and magnetic properties of m-N -methylpyridinium nitronyl nitroxide (abbreviated as m -MPYNN+) salts were studied. m- MPYNN +· ClO 4 −·( 1 3 )(acetone) is found to crystallize into the trigonal P 3 c 1 space group, where the m -MPYNN+ molecules exist as a dimer and the dimer units form a 2-D trinagular lattice. Temperature dependence of the magnetic susceptibility can be well interpreted in terms of a strong ferromagnetic intradimer interaction J 1 forming a triplet state and a weak antiferromagnetic interdimer interaction J 2 . There is a possibility that this spin system can be characterized as a spin-1 Kagome antiferromagnet at very low temperatures. m -MPYNN+ makes salts with various anions, I-, Cl-, BF 4 -, ClO 4 - etc. and their mixtures. In an isostructural solid-solution system, m -MPYNN+·(ClO 4 − ) x ·l− 1− x ( 1 3 )(acetone) (0≤ x ≤1), J 2 quickly weakens with increasing the ratio of the ClO 4 - ion, in contrast to little dependence of J 1 .

Anomalous physical properties of the low carrier concentration state in f-electron systems

Abstract Recent progress in studies on low carrier concentration systems of magnetically ordered and non-magnetic heavy Fermion metals are discussed. Successive steps in the high field magnetisation, the magnetic structure, and the influence of high pressure are reported and the relation with the observed Fermi surface for CeP is discussed. The origin of the low carrier concentration in USb is also discussed based on the first observation of dHvA oscillations. It is also unambiguously demonstrated that the unconventional heavy Fermion state of Yb4As3 is intrinsic and not due to impurities.

The specific heat of single crystal NdCu2

Abstract We present the measurements of the specific heat C of NdCu 2 on single crystal samples of high purity in the temperature range between 0.7 K and 70 K. We observed three peaks: two are first order peaks at T R1 = 3.97 K and T R2 = 4.22 K and one is the antiferromagnetic transition at T N = 6.50 K. The gap in the density of state of the antiferromagnetic spin wave band is found below T R2 . The specific heat observed below T R1 is well expressed by the gap type formula C = γT + β m T 3 exp(− δ / κ B T ). We show good correlation between the entropies of NdCu 2 and the magnetic resistivity measured along the crystal b -axis.

Phosphorylation of 13 kDa nuclear protein in hepatocarcinomas induced by peroxisome proliferators.

Peroxisome proliferators (PPs) are nongenotoxic compounds causing the emergence of hepatocellular carcinoma in rodents, but the mechanisms of the hepatocarcinogenesis have been unclear. The authors examined the changes in phosphorylation of nuclear proteins after treatment with (4-chloro-6-[2,3-xylidino]-2-pyrimidinylthio) acetic acid (Wy-14,643). Wy-14,643 (0.1% w/w in diet) was given orally to male F-344 rats for up to 80 wk. In the hepatocarcinomas induced by Wy-14,643, phosphorylation of 13 kDa nuclear protein (NP 13), which was resistant to alkaline treatment, was significantly increased. NP 13 phosphorylation gradually increased, dependent on treatment period. Furthermore, in the hepatocarcinomas induced by other PP, di(2-ethylhexyl)phthalate, increase in NP13-phospholyration was also observed. Therefore, NP 13-phospholyration may relate to development of preneoplastic or neoplastic lesions induced by PPs.

Heat capacity and magnetoresistance of the alloy of pristine and fully deuterated (DMeDCNQI)2Cu — Is the heavy electron model applicable?

Abstract We measured the electrical resistance of the title compounds in the metal—insulator—metal re-entrance transition regime as functions of temperature and magnetic field under pressure. The resistance was enhanced by the application of magnetic fields near the insulating state. We propose to ascribe this transition to the stabilization of the insulating state having paramagnetic spins. The heat capacity was also measured in vacuum in the range of 0.1 K to evaluate the electronic density of states. It suggests that the re-entrance transition is hardly explained in terms of the heavy electron model.

Transport and thermal properties of U3Rh4Sn13 and U5Ru6Sn18

Abstract Transport, magnetic and thermal properties of U 3 Rh 4 Sn 13 and U 5 Ru 6 Sn 18 have been investigated. For U 3 Rh 4 Sn 13 , the transport properties suggest Fermi-surface reconstruction below the magnetic phase transition at 18 K. U 5 Ru 6 Sn 18 exhibits various extraordinary transport properties, which are partly explained by the conduction electron scattering by 5f magnetic moments. A drastic suppression of specific heat C / T by applied magnetic field was observed for U 5 Ru 6 Sn 18 .