We report on de Haas-van Alphen ͑dHvA͒ effect measurements at ambient pressure and band-structure calculations for LaRhSi 3 and CeRhSi 3 , whose crystal structures lack space-inversion symmetry. For LaRhSi 3 , dHvA frequencies up to ϳ11 kT with effective masses up to ϳ1.6m e , where m e is the free-electron mass, are observed. The observed and the calculated Fermi surfaces are in satisfactory quantitative agreement. The energy splitting of bands due to the spin-orbit coupling is estimated to be of the order of 10 2 K. For CeRhSi 3 , dHvA frequencies up to ϳ12 kT with effective masses up to ϳ19m e are observed. The dHvA frequency branches are definitely different from those observed in LaRhSi 3 and are difficult to explain with the LaRhSi 3 Fermi surface. This leads to the conclusion that the Ce 4f electrons in CeRhSi 3 are itinerant in the antiferromagnetic state at ambient pressure. The Fermi surface resulting from a band-structure calculation in which the Ce 4f electrons are treated as itinerant can provide a plausible explanation for the observed frequency branches, although the quantitative agreement is rather limited. The comparison of the calculated density of states with the Sommerfeld coefficient gives the mass enhancement factor of 8.

In order to investigate the screening effect of a nuclear reaction in a liquid metal environment, thick-target yields of the 6 Li(d,) 4 He and 7 Li(p,) 4 He reactions were measured using a liquid Li target for incident energies between 22.5 and 70 keV. The modified SðEÞ factor [S Ã ðEÞ] for the liquid Li environment was deduced by dividing the measured yield by the energy integration of the penetration factor divided by the stopping power. It was shown that S Ã ðEÞ for the liquid environment is considerably larger than that for the atomic/molecular environment for both reactions. The difference in the screening energy between the two environments was deduced to be ÁU ¼ 235 AE 63 ( 6 Li+d) and 140 AE 82 eV ( 7 Li+p), although the screening energy for liquid Li has a large uncertainty with U liq $ 486{776 ( 6 Li+d) and 324-637 eV ( 7 Li+p) owing to the uncertainty of the astrophysical bare SðEÞ factors. This difference in the screening energy should be considered in such a way that, in liquid Li metal, conduction electrons and Li þ ions contribute to the screening in addition to bound electrons.

No abstract

We report the pressure dependence of antiferromagnetism and superconductivity in the heavy-fermion CeRhSi 3 on the magnetic field in the tetragonal basal plane. The anomaly of the resistivity at the antiferromagnetic transition changes in behavior with increasing pressure. This is caused by the monotonic reduction of the A coefficient in ðT Þ ¼ 0 þ AT with increasing pressure. The analysis of the pressure dependence of the resistivity strongly indicates that there is no enhancement of spin fluctuation in the vicinity of the pressure at which antiferromagnetism disappears. At the pressures where superconductivity occurs in the antiferromagnetic state, the ac susceptibility shows weak magnetic shielding with a large dissipation energy in the superconducting state. This probably indicates that the superconducting fluctuation is dominant under the magnetic order.

No abstract