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He, R.-H.*; Hashimoto, Makoto*; Karapetyan, H.*; Koralek, J. D.*; Hinton, J. P.*; Testaud, J. P.*; Nathan, V.*; Yoshida, Yoshiyuki*; Yao, H.*; Tanaka, Kiyohisa*; et al.
Science, 331(6024), p.1579 - 1583, 2011/03
Times Cited Count:278 Percentile:98.66(Multidisciplinary Sciences)The nature of the pseudogap phase of cuprate high-temperature superconductors is a major unsolved problem in condensed matter physics. We studied the commencement of the pseudogap state at temperature using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally doped Bi2201 crystals. We observed the coincident, abrupt onset at of a particle-hole asymmetric antinodal gap in the electronic spectrum, a Kerr rotation in the reflected light polarization, and a change in the ultrafast relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature (), entangled in an energy-momentum dependent manner with the preexisting pseudogap features, ushering in a ground state with coexisting orders.
Ueda, Kiyoshi*; Fukuzawa, Hironobu*; Liu, X.*; Sakai, Katsunori*; Prmper, G.*; Morishita, Yuichiro*; Saito, Norio*; Suzuki, Isao*; Nagaya, Kiyonobu*; Iwayama, Hiroshi*; et al.
Journal of Electron Spectroscopy and Related Phenomena, 166-167, p.3 - 10, 2008/11
Times Cited Count:23 Percentile:72.20(Spectroscopy)Interatomic Coulombic decay (ICD) in Ar, ArKr and Kr following Ar 2p or Kr 3d Auger decay has been investigated by means of momentum-resolved electron-ion-ion-coincidence spectroscopy. This sequential decay leads to Coulombic dissociation into dication and monocation. Simultaneously determining the kinetic energy of the ICD electron and the kinetic energy release between the two atomic ions, we could unambiguously identify the ICD channels. We find that, in general, spin conserved ICD, in which the singlet (triplet) dicationic state produced via the atomic Auger decay preferentially decays to the singlet (triplet) state, transferring the energy to the other atom, is faster than the spin-flip ICD, in which the Auger final singlet (triplet) dicationic state decays to the triplet (singlet) state.
Nagaya, Kiyonobu*; Yao, Makoto*; Hayakawa, Tetsuichiro*; Omasa, Yoshinori*; Kajihara, Yukio*; Ishii, Masashi*; Katayama, Yoshinori
Physical Review Letters, 89(24), p.243401_1 - 243401_4, 2002/12
Times Cited Count:16 Percentile:65.04(Physics, Multidisciplinary)Recently, we proposed a new method for the size-selective EXAFS(Extended X-ray absorption fine structure) of neutral-free culsters, in which not only the X-ray absorption process but also the deexitation process are utilized as the structural information. In order to verify this method experimentally, we have developed the synchronous measurements of EXAFS and photoelectron photoion coincidence and carried them out for a Se cluster beam by utilizing the third-generation intense X-ray source. The EXAFS spectra for Se small clusters have been obtained and compared critically with theoretical predictions.