Electrochemical synthesis and properties of CoO2, the x = 0 phase of the AxCoO2 systems (A = Li, Na)

Single-phase bulk samples of the "exotic" CoO2, the x = 0 phase of the AxCoO2 systems (A = Li, Na), were successfully synthesized through electrochemical de-intercalation of Li from pristine LiCoO2 samples. The samples of pure CoO2 were found to be essentially oxygen stoichiometric and possess a hexagonal structure consisting of stacked triangular-lattice CoO2 layers only. The magnetism of CoO2 is featured with a temperature-independent susceptibility of the magnitude of 10-3 emu/mol Oe, being essentially identical to that of a Li-doped phase, Li0.12CoO2. It is most likely that the CoO2 phase is a Pauli-paramagnetic metal with itinerant electrons.Comment: 12 pages, 3 figure

High-field phase diagram of the Haldane-gap antiferromagnet Ni(C5H14N2)2N3(PF6)Ni (C_5 H_{14} N_2)_2 N_3 (PF_6)

We have determined the magnetic phase diagram of the quasi-one-dimensional $S=$ 1 Heisenberg antiferromagnet $Ni (C_5 H_{14} N_2)_2 N_3 (PF_6)$ by specific heat measurements to 150 mK in temperature and 32 T in magnetic field. When field is applied along the spin-chain direction, a new phase appears at $H_{c2}\approx 14$ T. For the previously known phases of field-induced order, accurate determination is made of the power-law exponents of the ordering temperature near the zero-temperature critical field $H_c$, owing to the four-fold improvement of the minimum temperature over the previous work. The results are compared with the predictions based on the Bose-Einstein condensation of triplet excitations. Substituting deuterium for hydrogen is found to slightly reduce the interchain exchange.Comment: 6 pages, 6 figure

Evaluation of the Chemical and Biological Characteristics of Sake Lees

Sake lees (SLs), produced from brewing Japanese Sake and known to be rich in yeast, is expected to be an alternative of feed protein sources for ruminants. Previous studies showed that yeast improved the digestibility of fibers in ruminants. However, the nutrient composition and the numbers of live and dead yeast in the SLs, have large diversity because of the different brewing materials and processes. The objective of this study was to evaluate the chemical and biological characteristics of SLs with diverse brewing processes and storing periods (0-23 weeks). Seven types of SLs (SLs 1-7) were collected from two breweries. SLs 1, 2, 5 and 6 were made from liquefied rice under high-temperature saccharification method and SLs 3, 4 and 7 were made from steamed rice under general multiple parallel fermentation method. The crude protein (CP) contents of SLs from liquefied rice were higher than those from steamed rice (59.3-69.9% vs 32.8-51.4%DM). Ethanol concentrations were in the range of 6.1 to 11.2%FM in SLs 1-5. The numbers of live yeast (×104 CFU/ FM g) were ranged from 1,462 to 6,109 before storing, which dramatically decreased to 0-145 at 4 weeks’ storing at 4℃ in SLs 1-5. The numbers of dead yeast (×109 / FM g) were ranged from 0.7 to 3.0 before storing, which were stable during 4 weeks’ storing showing 0.5-4.6 in SLs 1-5. These results suggested that SLs, especially from liquefied rice, had high CP contents and substantial amounts of ethanol. The live yeast observed drastically disappeared, on the other hand, the numbers of dead yeast were stable under refrigeration. Further study is needed to evaluate the effect of supplementary SLs on digestibility in ruminants especially in roughage feeding condition

Nanoscale Defect Formation on InP(111) Surfaces after MeV Sb Implantation

We have studied the surface modifications as well as the surface roughness of the InP(111) surfaces after 1.5 MeV Sb ion implantations. Scanning Probe Microscope (SPM) has been utilized to investigate the ion implanted InP(111) surfaces. We observe the formation of nanoscale defect structures on the InP surface. The density, height and size of the nanostructures have been investigated here as a function of ion fluence. The rms surface roughness, of the ion implanted InP surfaces, demonstrates two varied behaviors as a function of Sb ion fluence. Initially, the roughness increases with increasing fluence. However, after a critical fluence the roughness decreases with increasing fluence. We have further applied the technique of Raman scattering to investigate the implantation induced modifications and disorder in InP. Raman Scattering results demonstrate that at the critical fluence, where the decrease in surface roughness occurs, InP lattice becomes amorphous.Comment: 18 pages, 9 figure

100m規模の氷山の移流に伴う表層水の変動

第6回極域科学シンポジウム分野横断セッション：[IG] 全球環境変動を駆動する南大洋・南極氷床11月17日（火）　国立極地研究所 2階 大会議

Anomalous superfluid density in quantum critical superconductors

When a second-order magnetic phase transition is tuned to zero temperature by a non-thermal parameter, quantum fluctuations are critically enhanced, often leading to the emergence of unconventional superconductivity. In these `quantum critical' superconductors it has been widely reported that the normal-state properties above the superconducting transition temperature $T_c$ often exhibit anomalous non-Fermi liquid behaviors and enhanced electron correlations. However, the effect of these strong critical fluctuations on the superconducting condensate below $T_c$ is less well established. Here we report measurements of the magnetic penetration depth in heavy-fermion, iron-pnictide, and organic superconductors located close to antiferromagnetic quantum critical points showing that the superfluid density in these nodal superconductors universally exhibit, unlike the expected $T$-linear dependence, an anomalous 3/2 power-law temperature dependence over a wide temperature range. We propose that this non-integer power-law can be explained if a strong renormalization of effective Fermi velocity due to quantum fluctuations occurs only for momenta $\bm{k}$ close to the nodes in the superconducting energy gap $\Delta(\bm{k})$. We suggest that such `nodal criticality' may have an impact on low-energy properties of quantum critical superconductors.Comment: Main text (5 pages, 3 figures) + Supporting Information (3 pages, 4 figures). Published in PNAS Early Edition on February 12, 201

Electrochemical synthesis and properties of CoO[sub 2], the x=0 phase of the A[sub x]CoO[sub 2] systems (A=Li,Na)

Single-phase bulk samples of the “exotic” CoO2, the x=0 phase of the AxCoO2 systems (A=Li,Na), were successfully synthesized through electrochemical deintercalation of Li from pristine LiCoO2 samples. The samples of pure CoO2 were found to be essentially oxygen stoichiometric and possess a hexagonal structure consisting of stacked triangular-lattice CoO2 layers only. The magnetism of CoO2 is featured with a temperature-independent susceptibility of the magnitude of 10−3emu/molOe, being essentially identical to that of a Li-doped phase, Li0.12CoO2. It is most likely that the CoO2 phase is a Pauli-paramagnetic metal with itinerant electrons.Peer reviewe