The superconductivity of Th//7//. //1(Fe, Co)//3, Th//7//. //1(Co, Ni)//3 and Th//7//. //1(Fe, Ni)//3 pseudo-binary compounds is reported. An unusual peak-and-valley structure is observed in the compositional variations of the superconducting transition temperatures. The same features in the data for the combined Th//7//. //1(Fe, Co)//3 and Th//7//. //1(Co, Ni)//3 systems are reproduced, although attenuated, in those for the Th//7//. //1(Fe, Ni)//3 system. It is argued that in the Th//7X//3 compounds with D10//2 structure the superconductivity is due to Th 6d-bands.
|Number of pages||4|
|State||Published - 1985|
Bibliographical noteFunding Information:
ThvFe3, Th7Co 3 and Th7Ni 3 are the only Th-rich compounds known to form with iron group elements. They all have the hexagonal D102 structure and become superconductors with transition temperatures T c of about 2 K \[1\]. The Fe, Co and Ni atoms are isolated from one another in cages of Th atoms, and the three compounds are Pauli paramagnets with essentially temperature-independent susceptibilities \[2\]. When the iron group elements are introduced as impurities into pure Th, a 1.36 K superconductor, Fe, Co and Ni are either negligibly soluble or little affect T c while Mn and Cr depress T c extremely rapidly \[3\]. T_hMn and ThCr are thought to be Kondo systems \[4\]; and Th7Mn 3 and Th7Cr3, of course, do not form. In ThvFe3, ThvCo 3 and ThTNi 3 the iron group 3d-shells are certainly filled; and their role in the superconductivity would seem to be minor. In another set * Research supported by the National Science Foundation under grants DMR 80-10530 and DMR 82-03690. * Present address: Laboratory of Nuclear Studies, Cornell University, Ithaca, NY 14853, USA.
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