MacDougall, G. J.*; Savici, A. T.*; Aczel, A. A.*; Birgeneau, R. J.*; Kim, H.*; Kim, S.-J.*; Ito, Toshimitsu*; Rodriguez, J. A.*; Russo, P. L.*; Uemura, Yasutomo*; et al.
Physical Review B, 81(1), p.014508_1 - 014508_7, 2010/01
MacDougall, G. J.*; Aczel, A. A.*; Carlo, J. P.*; Ito, Toshimitsu*; Rodriguez, J.*; Russo, P. L.*; Uemura, Yasutomo*; Wakimoto, Shuichi; Luke, G. M.*
Physical Review Letters, 101(1), p.017001_1 - 017001_4, 2008/07
We have performed zero-field muon spin rotation measurements on single crystals of LaSrCuO to search for spontaneous currents in the pseudo-gap state. By comparing measurements on materials across the phase diagram, we put strict upper limits on any possible time-reversal symmetry breaking fields that could be associated with the pseudo-gap. Comparison between experimental limits and proposed circulating current states effectively eliminates the possibility that such states exist in this family of materials.
MacDougall, G. J.*; Birgeneau, R. J.*; Kim, H.*; Kim, S.-J.*; Rodriguez, J.*; Russo, P. L.*; Savici, A. T.*; Uemura, Yasutomo*; Wakimoto, Shuichi; Wiebe, C. R.*; et al.
Physica B; Condensed Matter, 374-375, p.211 - 214, 2006/03
In the huge volume of research on the cuprates, there is very little that investigates the properties of the highly overdoped area of the phase diagram, where superconductivity disappears with increased carrier concentration. In the spirit of further exploring this region, we have performed the first known SR measurements of heavily overdoped single-crystalline LaSrCuO. We discovered an anomalous field-induced broadening of the internal magnetic field distribution. The broadening is linear in applied field and has a Curie-Weiss temperature dependence. Furthermore, the effect increases with doping above and is maximal at our highest doping (). Possible relaxation mechanisms are discussed.
Iemura, K.*; Otani, Shunsuke*; Suzuki, H.*; Takeda, Junichi*; Machida, Shuichi*; Tanabe, K.*; Takayanagi, Toshinobu*; Wakiya, K.*; Sekiguchi, M.*; Kanai, Yasuyuki*; et al.
Physical Review A, 64(6), p.062709_1 - 062709_14, 2001/12
We measured ejected electron spectra caused by autoionization of doubly excited states in He atoms; the excited He was made by double electron capture of low-energy He ions colliding with Ba atoms. Measurements were performed by means of zero degree electron spectroscopy at projectile energies from 40 to 20 keV. Electron spectra due to autoionization from the states He(2lnl) to He+(1s) for n2, and those from He(3lnl) to He(2s or 2p) for n3, were observed. Line peaks in the spectra were identified by comparing observed electron spectra with those of several theoretical calculations. It was found that doubly excited states of relatively high angular momenta such as the D and F terms were conspicuously created in a quite different manner from the cases of the production of doubly excited states by the use of photon, electron, or ion impacts on neutral He atoms. Rydberg states with large n values were observed with high population in both the He(2lnl) and He(3lnl) series.
Nishihata, Yasuo; Mizuki, Junichiro; Emura, Shuichi*; Uruga, Tomoya*
Journal of Synchrotron Radiation, 8, p.294 - 296, 2001/03
no abstracts in English
Nakata, Yoshiyuki*; Hara, Naoyuki*; Hirotsu, Yoshihiko*; Emura, Shuichi*; Makino, Akihiro*; Uruga, Tomoya*; Harada, Makoto*; Nishihata, Yasuo; Yoneda, Yasuhiro; Kubozono, Yoshihiro*
Japanese Journal of Applied Physics, 38(Suppl.38-1), p.404 - 407, 1999/06
The EXAFS spectra on Zr K-edge are investigated for as-formed Fe-7at%Zr-3at%B amorphous alloys and annealed ones at 693 K and 773 K for an hour in order to reveal local structural changes due to annealing. The analysis shows that the atomic distances of Fe-Zr and Zr-Zr pairs increase during annealing and approach those in a Fe3Zr or/and Fe2Zr metallic comound. The change in the atomic distances suggests that medium range ordered clusters should be formed during annealing.
Uruga, Tomoya*; Tanida, Hajime*; Yoneda, Yasuhiro; Takeshita, Kunikazu*; Emura, Shuichi*; Takahashi, Masao*; Harada, Makoto*; Nishihata, Yasuo; Kubozono, Yoshihiro*; Tanaka, Tsunehiro*; et al.
Journal of Synchrotron Radiation, 6(Part3), p.143 - 145, 1999/05
An x-ray absorption fine-structure (XAFS) spectroscopy beamline, BL01B1, was installed at a bending magnet source at SPring-8 and has been open to users since October 1997. It was designed for XAFS experiments covering a wide energy range. Position tables and automatical control programs were established to adjust the x-ray optics and achieve the designed performance of the beamline under each experimental condition. This has enabled conventional XAFS measurements to be made with a good data quality from 4.5 to 110 keV.
Kubozono, Yoshihiro*; Mimura, Kazue*; Takabayashi, Yasuhiro*; Maeda, Hironobu*; Kashino, Setsuo*; Emura, Shuichi*; Nishihata, Yasuo; Uruga, Tomoya*; Tanaka, Tsunehiro*; Takahashi, Masao*
Journal of Synchrotron Radiation, 6(Part3), p.564 - 566, 1999/05
The Rb K-edge XAFS spectra for the stable phase of RbC60 which is a quasi one-dimensional polymer were measured in the temperature range from 14.6 to 210 K in order to clarify the origin of the metal-insulator transition around 50 K. The distances and mean-square relative displacements between the Rb atom and the neighboring C atoms determined by XAFS exhibited no change around 50 K, implying that the metal-insulator transition originates from the SDW instablity.
Takahashi, Masao*; Harada, Makoto*; Watanabe, Iwao*; Uruga, Tomoya*; Tanida, Hajime*; Yoneda, Yasuhiro; Emura, Shuichi*; Tanaka, Tsunehiro*; Kimura, Hidekazu*; Kubozono, Yoshihiro*; et al.
Journal of Synchrotron Radiation, 6(3), p.222 - 224, 1999/05
no abstracts in English