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Title: Superconductivity in the Nb-Ru-Ge σ phase

Abstract

Here, we show that the previously unreported ternary σ-phase material Nb 20.4Ru 5.7Ge 3.9 (Nb 0.68Ru 0.19Ge 0.13) 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 Nb 20.4Ru 5.7Ge 3.9 is 91 mJ mol-f.u. -1K -2 (~3 mJ mol-atom -1K -2) and the specific heat anomaly at the superconducting transition, ΔC/γT c, is approximately 1.38. The zero-temperature upper critical field (µ 0Hc 2(0)) was estimated to be 2 T by resistance data. Field-dependent magnetization data analysis estimated µ 0Hc 1(0) to be 5.5 mT. Thus, the characterization shows Nb 20.4Ru 5.7Ge 3.9 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.

Authors:
 [1];  [2];  [3];  [1];  [3];  [1]
  1. Princeton Univ., Princeton, NJ (United States)
  2. Louisiana State Univ., Baton Rouge, LA (United States)
  3. Gdansk Univ. of Technology, Gdansk (Poland)
Publication Date:
Research Org.:
Princeton Univ., NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1411888
Alternate Identifier(s):
OSTI ID: 1411803
Grant/Contract Number:  
FG02-98ER45706
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review Materials
Additional Journal Information:
Journal Volume: 1; Journal Issue: 7; Journal ID: ISSN 2475-9953
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Carnicom, Elizabeth M., Xie, Weiwei, Sobczak, Zuzanna, Kong, Tai, Klimczuk, Tomasz, and Cava, R. J. Superconductivity in the Nb-Ru-Geσ phase. United States: N. p., 2017. Web. doi:10.1103/PhysRevMaterials.1.074802.
Carnicom, Elizabeth M., Xie, Weiwei, Sobczak, Zuzanna, Kong, Tai, Klimczuk, Tomasz, & Cava, R. J. Superconductivity in the Nb-Ru-Geσ phase. United States. doi:10.1103/PhysRevMaterials.1.074802.
Carnicom, Elizabeth M., Xie, Weiwei, Sobczak, Zuzanna, Kong, Tai, Klimczuk, Tomasz, and Cava, R. J. Thu . "Superconductivity in the Nb-Ru-Geσ phase". United States. doi:10.1103/PhysRevMaterials.1.074802. https://www.osti.gov/servlets/purl/1411888.
@article{osti_1411888,
title = {Superconductivity in the Nb-Ru-Geσ phase},
author = {Carnicom, Elizabeth M. and Xie, Weiwei and Sobczak, Zuzanna and Kong, Tai and Klimczuk, Tomasz and Cava, R. J.},
abstractNote = {Here, 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-1K-2) and the specific heat anomaly at the superconducting transition, ΔC/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.},
doi = {10.1103/PhysRevMaterials.1.074802},
journal = {Physical Review Materials},
number = 7,
volume = 1,
place = {United States},
year = {2017},
month = {12}
}

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