Superconductivity in the Nb-Ru-Ge σ phase

Elizabeth M. Carnicom; Weiwei Xie; Zuzanna Ryżyńska; Tai Kong; Tomasz Klimczuk; R.j. Cava

doi:10.1103/physrevmaterials.1.074802

Superconductivity in the Nb-Ru-Ge σ phase

Abstract

We show that the previously unreported ternary σ-phase material Nb20.4Ru5.7Ge3.9 (Nb0.68Ru0.19Ge0.13) is a superconductor with a critical temperature of 2.2 K. Temperature-dependent magnetic susceptibility, resistance, and specific-heat measurements were used to characterize the superconducting transition. The Sommerfeld constant γ for Nb20.4Ru5.7Ge3.9 is 91 mJ mol f.u. −1K−2 (∼3 mJ mol atom−1 K−2) and the specific-heat anomaly at the superconducting transition, C/γTc, is approximately 1.38. The zero-temperature upper critical field [μ0Hc2(0)] was estimated to be 2 T by resistance data. Field-dependent magnetization data analysis estimated μ0Hc1(0) to be 5.5 mT. Thus, the characterization shows Nb20.4Ru5.7Ge3.9 to be a type-II BCS superconductor. This material appears to be the first reported ternary phase in the Nb-Ru-Ge system, and the fact that there are no previously reported binary Nb-Ru, Nb-Ge, or Ru-Ge σ phases shows that all three elements are necessary to stabilize the material. An analogous σ phase in the Ta-Ru-Ge system did not display superconductivity above 1.7 K, which suggests that electron count cannot govern the superconductivity observed. Preliminary characterization of a possible superconducting σ phase in the Nb-Ru-Ga system is also reported.

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Authors (6)

Elizabeth M. Carnicom
Weiwei Xie
Zuzanna Ryżyńska (formerly: Zuzanna Sobczak)
Tai Kong
Tomasz Klimczuk prof. dr hab. inż.
R.j. Cava

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DOI:: Digital Object Identifier (open in new tab) 10.1103/PhysRevMaterials.1.074802
License: Copyright (2017 American Physical Society)

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Category:: Articles
Type:: publikacja w in. zagranicznym czasopiśmie naukowym (tylko język obcy)
Published in:: Physical Review Materials no. 1, edition 7, pages 1 - 7,
ISSN: 2475-9953
Language:: English
Publication year:: 2017
Bibliographic description:: Carnicom E., Xie W., Sobczak Z., Kong T., Klimczuk T., Cava R.. Superconductivity in the Nb-Ru-Ge σ phase. Physical Review Materials, 2017, Vol. 1, iss. 7, s.1-7
DOI:: Digital Object Identifier (open in new tab) 10.1103/physrevmaterials.1.074802
Verified by:: Gdańsk University of Technology