TY - JOUR
T1 - Superconducting properties of a mixed anion layered compound, Ca and F co-doped LaFeAsO with T c = 31.5 K
AU - Kaneyasu, Kodai
AU - Sakagami, Ryosuke
AU - Matoba, Masanori
AU - Kamihara, Yoichi
N1 - Funding Information:
Acknowledgments This work was partially supported by the research grant of Keio University. YK was supported by the Japan Society for the Promotion of Science (JSPS) through a Grant-in-Aid for scientific Research (B) (grant no. 17H03239). We are indebted to Professor M. Miura (Seikei University, Japan) for his helpful advice for the analysis on transport properties. ORCID iDs Kodai Kaneyasu https://orcid.org/0000-0003-4526-0909
Publisher Copyright:
© 2019 The Japan Society of Applied Physics.
PY - 2019/3/1
Y1 - 2019/3/1
N2 - Polycrystalline Ca and F co-doped LaFeAsO samples (La1-xCaxFeAsO1-yFy) were synthesized by solid-state reactions. Samples with nominal composition: (y - x) ≤ 0.05 did not show superconductivity at temperatures T > 4.2 K, although an anomalous kink of the ρ-T curves, which is related to crystallographic phase transitions, was observed at T ∼ 150 K. Samples with nominal composition: (y - x) ≥ 0.15 did exhibit superconductivity. The superconducting transition temperature (T c) of co-doped LaFeAsO with nominal composition: (x, y) = (0.25, 0.50) was determined to be T c = 31.5 K, which is higher than the highest T c value observed for LaFeAsO1-xFx materials synthesized under ambient pressure.
AB - Polycrystalline Ca and F co-doped LaFeAsO samples (La1-xCaxFeAsO1-yFy) were synthesized by solid-state reactions. Samples with nominal composition: (y - x) ≤ 0.05 did not show superconductivity at temperatures T > 4.2 K, although an anomalous kink of the ρ-T curves, which is related to crystallographic phase transitions, was observed at T ∼ 150 K. Samples with nominal composition: (y - x) ≥ 0.15 did exhibit superconductivity. The superconducting transition temperature (T c) of co-doped LaFeAsO with nominal composition: (x, y) = (0.25, 0.50) was determined to be T c = 31.5 K, which is higher than the highest T c value observed for LaFeAsO1-xFx materials synthesized under ambient pressure.
UR - http://www.scopus.com/inward/record.url?scp=85063332180&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85063332180&partnerID=8YFLogxK
U2 - 10.7567/1347-4065/aafec4
DO - 10.7567/1347-4065/aafec4
M3 - Article
AN - SCOPUS:85063332180
SN - 0021-4922
VL - 58
JO - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
JF - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
IS - 3
M1 - 030911
ER -