The accumulation of helium entities produced through beta-decay of tritium represents a major obstacle for the process of muon-catalyzed fusion in hydrogen. Using ab initio Hartree-Fock cluster ...methods at the MP2 level, we have investigated the trapping properties of He+, He0 and (He-H)+ impurities at interstitial sites in solid hydrogen. Our results indicate that the positive charge of He+ is distributed to the surrounding H_2 molecules, resulting in a significant lowering of the energy which leads to a large binding energy of about 8.3~eV for He+. On the other hand, the neutral He0 remains essentially unbound. Both entities might however be trapped equally strongly due to the diffusion barrier involved when moving to an adjacent interstitial site. Consequences of these findings for the trapping of (He-H)+ will be discussed as well. Finally, results of our studies on the possibility of helium nucleation in solid hydrogen will be presented.
Effects of the Cu-site substitution on the 1/8 anomaly in the Bi-2212 and Y-123 phases and also on the anomaly at x = 0.21 in La sub(2-x)Sr sub(x)CuO sub(4) (LSCO) have been investigated from the ...transport, muon-spin relaxation and neutron-scattering measurements. It is suggested that the dynamical stripe correlations of spins and holes exist in the Bi-2212 and Y-123 phases as well as in the La-214 phase and that they tend to be pinned by Zn at the hole concentration of similar to1/8 per Cu in the high-T sub(c) cuprates and also at x = 0.21 in LSCO. Based upon the stripe-pinning model, universal properties in the high-T sub(c) cuprates that partially substituted Zn is a strong scatterer and that the Zn substitution markedly suppresses the superconductivity are also discussed. copyright 2001 Elsevier Science B.V. All rights reserved.
The so-called 1/8 effect, namely, the anomalous suppression of superconductivity at the hole concentration per Cu in the CuO{sub 2} plane, p, {approximately}1/8 has been investigated in the partially ...Zn-substituted Bi-2212 and Y-123 phases by measuring the Hall effect and the muon spin relaxation ({mu}SR). The Hall angle has been found to exhibit large enhancement at p {approximately} 1/8 in Bi{sub 2}Sr{sub 2}Ca{sub 1{minus}x}Y{sub x} (Cu{sub 1{minus}y}Zn{sub y}){sub 2}O{sub 8{delta}} with y = 0.025. In YBa{sub 2}Cu{sub 3{minus}2y}Zn{sub 2y}O{sub 7{minus}{delta}} with y = 0.025, anomalous enhancement of the muon spin depolarization has been observed at p {approximately} 1/8, indicating that the magnetic correlation between Cu spins is enhanced at p {approximately} 1/8. These results support the stripe model and the proposition that the 1/8 effect is common to all high-{Tc} cuprates with the CuO{sub 2} plane.
A new measurement of the anomalous magnetic moment (G-2 factor) of the muon to a precision of 0.35 p.p.m. is being undertaken with the AGS at Brookhaven National Laboratory. It will involve a ...precision superferric storage ring with a magnetic field of 1.5 T and a radius of 7 m for 3.1 GeV/c muons. The magnetic field in the storage region must be homogeneous to one part in 10/sup 6/ and the effective field averaged around the ring must be known to 1 part in 10/sup 7/. The design status of the superferric storage ring and of the techniques planned for magnetic-field control and measurement are presented. Perturbation field calculations for the iron and coil configuration, considerations on the superconducting coil, shimming and measurement techniques, and plans for a test magnet program are discussed.< >
Itinerant magnetism of LaNi 3 Tazuke, Y.; Murayama, S.; Nishiyama, K. ...
Journal of magnetism and magnetic materials,
1995, Letnik:
140
Journal Article
Recenzirano
LaNi
3 shows a non-ferromagnetic ordered phase in zero field below about 50 K, and metamagnetism in non-zero field. Zero-field μSR spectra show an antiferromagnetic phase below about 50 K. From the ...longitudinal-field μSR spectra, small Ni moments of about 0.03 μ
B are estimated.
