| Project/Area Number |
16540327
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | University of Hyogo |
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Principal Investigator |
SUMIYAMA Akihiko University of Hyogo, Graduate School of Material Science, Assistant Professor, 物質理学研究科, 助教授 (30226609)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | heavy-fermion superconductor / Josephson effect / anisotropic superconductivity / d-wave superconductivity |
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| Research Abstract |
The anisotropic order parameters of heavy-fermion superconductors have been investigated for UPt_3, CeIrIn_5 and CePt_3Si using Josephson junctions, especially Josephson interferometers that can detect the phase difference of the order parameter between two directions.
The corner junction on the UPt_3 faces perpendicular to the a[112^^-0] and b[101^^-0] axes has not shown a behavior indicating the phase shift of the order parameter between the a- and b-axis directions thus far. Even if the geometric asymmetry of the corner junction is taken into account, this result contradicts, for example, the two-dimensional E_<2u> scenario for the order parameter in UPt_3.
The magnetic-field modulation of the Josephson critical current between a single-crystal CeIrIn_5 and an s-wave superconductor has shown a nearly ideal Fraunhofer pattern in the [100] direction and a small deviation from that pattern in the [110] direction. The indication of the d-wave superconductivity has not been observed clearly for the corner junction on the (100) and (010) faces, probably because of the asymmetry of the junction.
In the magnetic-field dependence of I_c between a single crystal CePt_3Si and Al, a dominant maximum peak at zero field has been observed only for the junction on the a-axis face thus far, indicating that the Josephson effect is allowed at least for current flow parallel to the a axis. The randomly oscillating pattern for the junction on the c-axis face may be ascribed to the magnetic-flux trapping or the broken time-reversal symmetry in noncentrosymmetric superconductors.
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