Search for Magnetic-Field-Induced-Superconductivity in Heavy Fermion Systems.

寻找重费米子系统中的磁场感应超导性。

基本信息

批准号：
61460034
负责人：
KOBAYASHI Norio
金额：
$ 4.35万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1988
项目状态：
已结题

项目摘要

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

在繁重的费米昂系统和磁性超导系统中，Tachiki等人预测了高磁场区域中重入超导的可能性。这种恢复行为称为“磁场诱导的抗药性”（MFIS）。根据他们的预测，Isino等人在Chevrel相化合物中发现了MFI，EU_ <1-X> sn_xmo_6s_7。但是，在繁重的费米昂系统中，尚未发现MFI。我们执行了该项目，以阐明eu_ <1-x> sn_xmo_6s_7中MFI的起源，并在具有稀土元素（RE）或铀元素的重型费米昂系统中搜索MFI的可能性。1。在磁场下的电阻最多23吨，并且在磁场下的特定热量最多是Compounds EU_ <0.8> sn_ <0.2> mo_6s_ <7-Y> se_y（0 y 0.7）。特定的热量显示了具有磁矩的 ^8S_ <7/2>中的eN ^<2+>离子引起的肖特基贡献。此外，我们已经观察到了Hyste…在田间范围内的电阻中的更多恢复，其中超导不良抗传导性过渡出现。磁滞的结果证明，作用在传导电子旋转上的净磁场的方向与所施加的场相反。从这个事实中，得到证实2。几种含有稀土元素（CE，LA，YB）和UTX类型（T = PD，Pt，Pt，Ni和X = GE，SI，IN）化合物的几种TH_2CR_2SI_2类型化合物是通过弧形搅拌制备的。通过电阻，磁化和特定的热测量结果研究了这些化合物的性能。在这些化合物中，lapd_2ge_2，ybpd_2ge_2和unisi的超导性。 lapd_2ge_2和ybpd_2ge_2显示了通常的BC，例如超导性，而UNISI的行为较弱。但是，在我们的样品中找不到小额信贷机构。继续研究包含U的超导化合物。较少的