1988 Fiscal Year Final Research Report Summary
Search for Magnetic-Field-Induced-Superconductivity in Heavy Fermion Systems.
| Project/Area Number |
61460034
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
物性一般（含極低温･固体物性に対する理論）
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
KOBAYASHI Norio Institute for Materials Research, Tohoku University, 金属材料研究所, 助教授 (40111306)
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| Co-Investigator(Kenkyū-buntansha) |
IWASAKI Hideo Institute for Materials Research, Tohoku University, 金属材料研究所, 助手 (70168558)
KOYAMA Tomio Institute for Materials Research, Tohoku University, 金属材料研究所, 助手 (30153696)
MITSUGASHIRA Toshiaki Institute for Materials Research, Tohoku University, 金属材料研究所, 助教授 (30005938)
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| Project Period (FY) |
1986 – 1988
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| Keywords | Superconductivity / Heavy Fermion / Magnetic Superconductor / 重いフェルミ粒子 |
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| Research Abstract |
In heavy Fermion systems and magnetic superconducting systems, the possibility of the reentrant superconductivity in the high magnetic field region has been predicted by Tachiki et al. This reentrant behavior is called as "magnetic-field-induced-superconductivity"(MFIS). Following their prediction, Isino et al descovered the MFIS in a Chevrel Phase compound, Eu_<1-x>Sn_xMo_6S_7. However, in heavy Fermion systems, the MFIS has not been discovered. We performed this project in order to clarify the origin of the MFIS in Eu_<1-x>Sn_xMo_6S_7 and to search for the possibility of the MFIS in the heavy Fermion systems with rare earth elements (RE) or Uranium element.
1. The electrical resistance under magnetic fields up to 23 T and the speciffic heat under fields up to 6 T of the compounds Eu_<0.8>Sn_<0.2>Mo_6S_<7-y>Se_y(0 y 0.7) have been measured. The specific heat shows Schottky contribution due to En^<2+> ions in ^8S_<7/2>, which have magnetic moments. Furthermore we have observed the hyste
… More
resis of the electrical resistance in the field range where superconductive-normal-superconductive transition appear. This result on the hysteresis prove that the direction of the net magnetic field acting on the conduction electron spins is opposite to that of the applied field. From this fact, it is confirmed directly that the mechanism of the MFIS in this system oiriginates from the jaccarino-peter effect. 2. Several Th_2Cr_2Si_2 type compounds containing rare earth elements (Ce, La, Yb) and UTX type (T=Pd, Pt, Ni and X=Ge, Si, In) compounds were prepared by an arc-melting. The properties of these compounds were investigated by the electrical resistance, magnetization and specific heat measurements. Among these compounds, the superconductivity was observed in LaPd_2Ge_2, YbPd_2Ge_2 and UNiSi. While LaPd_2Ge_2 and YbPd_2Ge_2 show the usual BCS like superconductivity, UNiSi behaves weak heavy fermion properties. however, the MFIS was not found in our samples. Investigations of superconducting compounds containing u are continued. Less
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