TY - JOUR
T1 - Superconductivity in the Nb-Ru-Ge σ phase
AU - Carnicom, Elizabeth M.
AU - Xie, Weiwei
AU - Sobczak, Zuzanna
AU - Kong, Tai
AU - Klimczuk, Tomasz
AU - Cava, R. J.
N1 - Publisher Copyright:
© 2017 American Physical Society.
PY - 2017/12/7
Y1 - 2017/12/7
N2 - 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 91mJmolf.u.-1K-2 (∼3mJmolatom-1K-2) and the specific-heat anomaly at the superconducting transition, ΔC/γTc, is approximately 1.38. The zeroerature 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.
AB - 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 91mJmolf.u.-1K-2 (∼3mJmolatom-1K-2) and the specific-heat anomaly at the superconducting transition, ΔC/γTc, is approximately 1.38. The zeroerature 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.
UR - http://www.scopus.com/inward/record.url?scp=85054626106&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85054626106&partnerID=8YFLogxK
U2 - 10.1103/PhysRevMaterials.1.074802
DO - 10.1103/PhysRevMaterials.1.074802
M3 - Article
AN - SCOPUS:85054626106
SN - 2475-9953
VL - 1
JO - Physical Review Materials
JF - Physical Review Materials
IS - 7
M1 - 074802
ER -