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Title: Superconductivity and long range magnetic order in ternary rare earth iron silicides

Thesis/Dissertation ·
OSTI ID:6830874

Low temperature heat capacity measurements on three superconducting ternary rare-earth iron silicides, Lu/sub 2/Fe/sub 3/Si/sub 5/, Sc/sub 2/Fe/sub 3/Si/sub 5/ and Y/sub 2/Fe/sub 3/Si/sub 5/, indicate a number of unusual features in the superconducting state of these materials. These materials show a large linear term in the superconducting heat capacity and a reduced normalized jump in the specific heat at T/sub c/. These data suggest a significant fraction of the conduction electrons in these materials do not participate in the superconducting state but instead remain normal well below the superconducting transition temperature. A two band model is proposed to explain these and previously reported anomalous properties of these materials. Low temperature heat capacity measurements on the compounds RE/sub 2/Fe/sub 3/Si/sub 5/, RE = Sm, Gd-Yb, from 0.5 K to 30 K confirm previously reported antiferromagnetic ordering temperatures for RE = Gd-Tm and indicate that the compounds Sm/sub 2/Fe/sub 3/Si/sub 5/ and Yb/sub 2/Fe/sub 3/Si/sub 5/ also order antiferromagnetically. The magnetic behavoir of Yb in this system is consistent with lattice parameter determinations which indicate Yb is in the trivalent state rather than the more usual nonmagnetic divalent state. No evidence is found in the heat capacity data, even on careful inspection, for superconductivity in any of these antiferromagnetically ordered compounds.

Research Organization:
Iowa State Univ. of Science and Technology, Ames (USA)
DOE Contract Number:
W-7405-ENG-82
OSTI ID:
6830874
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English