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electronic states in CeIrSi
studied by angle-resolved Ce 3
resonance photoemission spectroscopyOkochi, Takuo*; Toshimitsu, Takafumi*; Yamagami, Hiroshi; Fujimori, Shinichi; Yasui, Akira; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Miyauchi, Yuichiro*; et al.
Journal of the Physical Society of Japan, 78(8), p.084802_1 - 084802_6, 2009/08
Times Cited Count：10 Percentile：54.5(Physics, Multidisciplinary)We have applied angle-resolved Ce 3
4 resonance photoemission spectroscopy to the non-centrosymmetric pressure-induced superconductor CeIrSi and obtained the 4 band-structure and Fermi surfaces. We have found that the Ce 4 states are located mainly near the Fermi level and that the photoemission intensity derived from the dispersive conduction bands across the Fermi level shows considerable resonant enhancement. In addition, the band structure and Fermi surfaces of CeIrSi are different from those of the non- reference compound, LaIrSi and the difference is well explained by the band structure calculated within the local density approximation (LDA). These results strongly suggest that the Ce 4 electrons in CeIrSi are well hybridized with conduction bands and form itinerant electronic states.
realized at the quantum critical pointSettai, Rikio*; Kawai, Tomoya*; Miyauchi, Yuichiro*; Okuda, Yusuke*; Onuki, Yoshichika; Takeuchi, Tetsuya*; Tateiwa, Naoyuki; Matsuda, Tatsuma; Haga, Yoshinori; Harima, Hisatomo*
Kotai Butsuri, 43(8), p.459 - 474, 2008/08
The magnetic transition temperature of an antiferromagnet CeIrSi decreases with increasing hydrostatic pressure, and finally superconductivity appears. An exotic superconducting symmetry is expected because of the absence of the inversion center in the crystal structure. One of the prominent features is the anomalously large upper critical field observed around the quantum critical point.
without inversion centerTateiwa, Naoyuki; Haga, Yoshinori; Ikeda, Shugo; Matsuda, Tatsuma; Yamamoto, Etsuji; Okuda, Yusuke*; Miyauchi, Yuichiro*; Settai, Rikio*; Onuki, Yoshichika*
Physica B; Condensed Matter, 403(5-9), p.1156 - 1158, 2008/04
Times Cited Count：1 Percentile：6.29(Physics, Condensed Matter)We present the result of an antiferromagnet CeIrSi without inversion center by measureing the heat capacity and the electrical resistivity of CeIrSi. Both physical quantities were measured in the same run for the same single crystal sample. A huge heat capacity anomaly was observed at the superconducting transition temperature 
= 1.6 K where the zero-resistivity was observed. The jump of the heat capacity 
is 5.7 
0.1 at 2.58 GPa. This value is the largest among previously reported superconducting materials, indicating the strong coupling superconductivity. The electronic specific heat coefficient just above is roughly estimated to be 100 20 mJ/K
mol at 2.58 GPa, which is the same as 
= 120 20 mJ/Kmol at ambient pressure.
Si and CeIrSi without inversion symmetry in the crystal structureOnuki, Yoshichika; Miyauchi, Yuichiro*; Tsujino, Masahiko*; Ida, Yuki*; Settai, Rikio*; Takeuchi, Tetsuya*; Tateiwa, Naoyuki; Matsuda, Tatsuma; Haga, Yoshinori; Harima, Hisatomo*
Journal of the Physical Society of Japan, 77(Suppl.A), p.37 - 42, 2008/00
Times Cited Count：6 Percentile：43.12(Physics, Multidisciplinary)Superconducting upper critical field of CePtSi and CeIrSi without inversion symmetry was studied in detail. In CePtSi coexisting with antiferromagnetism, rather isotropic critical field was observed. On the other hand, huge anisotropy was detected in CeIrSi. These results are discussed in connection with the formation of the heavy fermion state.
and CeIrSi with the non-centrosymmetric crystal structureOkuda, Yusuke*; Miyauchi, Yuichiro*; Ida, Yuki*; Takeda, Yuji*; Tonohiro, Chie*; Ozuchi, Yasuhiro*; Yamada, Tsutomu*; Nguyen, D.; Matsuda, Tatsuma; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 76(4), p.044708_1 - 044708_11, 2007/04
Times Cited Count：87 Percentile：91.73(Physics, Multidisciplinary)Single crystals of LaIrSi and CeIrSi were grown by the Czochralski pulling method in a tetra-arc furnace and the magnetic and superconducting properties, together with super- conductivity in CeIr
Co
Si, were clarified by measuring the electrical resistivity, specific heat, magnetic susceptibility, magnetization and de Haas-van Alphen (dHvA) effect. From the results of the dHvA experiment for LaIrSi, the Fermi surface is found to split into two Fermi surfaces due to the spin-orbit interaction arising from the non-centrosymmetric crystal structure. The electronic state of CeIrSi is tuned from the antiferro- magnetic state to the superconducting state by applying pressure. The upper critical field H
(0) at a pressure of 2.65 GPa is found to be highly anisotropic. Large magnitude and anisotropy of H(0) in CeIrSi are consistent with the theoretical prediction for superconductivity in the non-centrosymmetric crystal structure.
under high pressureTateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma; Ikeda, Shugo; Miyauchi, Yuichiro*; Okuda, Yusuke*; Settai, Rikio*; Onuki, Yoshichika
no journal, ,
Recently, non-centrosymmetric superconductors have attracted much attention from a view point of a mixed parity of a superconducting pair wave function. CeIrSi crystalizes in the tetragonal BaNiSn-type crystal structure. It shows an antiferromagnetic ordering at 
= 5.0 K and becomes a superconductor above 2 GPa. In this study, we have investigated CeIrSi by measurements of the heat capacity and electrical resistivity under high pressure. We will discuss the bulk superconducting phase.
and LaIrSi by angle-resolved photoemission spectroscopyToshimitsu, Takafumi; Okochi, Takuo; Yasui, Akira; Kobayashi, Masaki*; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Miyauchi, Yuichiro*; et al.
no journal, ,
no abstracts in English
by soft X-ray angle-resolved resonant photoemission spectroscopyOkochi, Takuo; Yasui, Akira; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi*; Yamagami, Hiroshi; Miyauchi, Yuichiro*; Okuda, Yusuke*; Settai, Rikio*; et al.
no journal, ,
We have investigated the bulk 4 electronic structure of the non-centrosymmetric superconductor, CeIrSi by soft X-ray angle-resolved photoemission spectroscopy. We have performed the angle-resolved 3
-4 resonant photoemission and the comparison of the angle-resolved photoemission spectra of CeIrSi with those of non- reference compound, LaIrSi and revealed that the 4 states of CeIrSi well hybridized with the non- conduction bands.
