Two-gap superconducting properties of alkaline-earth intercalated Ax(NH3)Fe2Se2 (A = Ba or Sr)

Yung Yuan Hsu; Yu Bo Li; Shou Ting Jian; Gu Kuei Li; Ming Cheng Yang

doi:10.1088/0953-2048/29/3/035005

Two-gap superconducting properties of alkaline-earth intercalated A_x(NH₃)Fe₂Se₂ (A = Ba or Sr)

Yung Yuan Hsu, Yu Bo Li, Shou Ting Jian, Gu Kuei Li, Ming Cheng Yang

Department of Physics

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

Abstract

Superconducting properties were studied on high quality superconductors Bax(NH₃)Fe₂Se₂ (T_c= 39 K) and Srx(NH₃)Fe₂Se₂ (Tc = 44 K) prepared by intercalating Ba/Sr atoms into tetragonal β-FeSe by liquid ammonia. The elongated c-axis and almost unchanged a-axis of Bax(NH₃)Fe₂Se₂, compared with β-FeSe, suggests an unchanged intra- Fe₂Se₂-layer structure and the T_c enhancement is due to a 3D to 2D-like Fermi surface transformation. The superconducting coherent lengths (0), the Ginzburg-Landau parameters κ and penetration depths (0) obtained from the extrapolated lower and upper critical fields B_c1 (0) and B_c2 (0) indicate that both compounds are typical type-II superconductors. The temperature dependence of 1/l2(T) of Bax(NH₃)Fe₂Se₂ deduced from the low-field magnetic susceptibility shows a twogap s-wave behavior with superconducting gaps of δ₁ = 6.47 meV and δ₂= 1.06 meV.

Original language	English
Article number	035005
Journal	Superconductor Science and Technology
Volume	29
Issue number	3
DOIs	https://doi.org/10.1088/0953-2048/29/3/035005
Publication status	Published - 2016 Jan 22

Keywords

Ginzburg-Landau parameter
alkaline-earth intercalated FeSe
iron chacogenide
penetration depth
two-gap s-wave superconductor

ASJC Scopus subject areas

Ceramics and Composites
Condensed Matter Physics
Metals and Alloys
Electrical and Electronic Engineering
Materials Chemistry

Access to Document

10.1088/0953-2048/29/3/035005

Cite this

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title = "Two-gap superconducting properties of alkaline-earth intercalated Ax(NH3)Fe2Se2 (A = Ba or Sr)",

abstract = "Superconducting properties were studied on high quality superconductors Bax(NH3)Fe2Se2 (Tc= 39 K) and Srx(NH3)Fe2Se2 (Tc = 44 K) prepared by intercalating Ba/Sr atoms into tetragonal β-FeSe by liquid ammonia. The elongated c-axis and almost unchanged a-axis of Bax(NH3)Fe2Se2, compared with β-FeSe, suggests an unchanged intra- Fe2Se2-layer structure and the Tc enhancement is due to a 3D to 2D-like Fermi surface transformation. The superconducting coherent lengths (0), the Ginzburg-Landau parameters κ and penetration depths (0) obtained from the extrapolated lower and upper critical fields Bc1 (0) and Bc2 (0) indicate that both compounds are typical type-II superconductors. The temperature dependence of 1/l2(T) of Bax(NH3)Fe2Se2 deduced from the low-field magnetic susceptibility shows a twogap s-wave behavior with superconducting gaps of δ1 = 6.47 meV and δ2= 1.06 meV.",

keywords = "Ginzburg-Landau parameter, alkaline-earth intercalated FeSe, iron chacogenide, penetration depth, two-gap s-wave superconductor",

author = "Hsu, {Yung Yuan} and Li, {Yu Bo} and Jian, {Shou Ting} and Li, {Gu Kuei} and Yang, {Ming Cheng}",

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T1 - Two-gap superconducting properties of alkaline-earth intercalated Ax(NH3)Fe2Se2 (A = Ba or Sr)

AU - Hsu, Yung Yuan

AU - Li, Yu Bo

AU - Jian, Shou Ting

AU - Li, Gu Kuei

AU - Yang, Ming Cheng

PY - 2016/1/22

Y1 - 2016/1/22

N2 - Superconducting properties were studied on high quality superconductors Bax(NH3)Fe2Se2 (Tc= 39 K) and Srx(NH3)Fe2Se2 (Tc = 44 K) prepared by intercalating Ba/Sr atoms into tetragonal β-FeSe by liquid ammonia. The elongated c-axis and almost unchanged a-axis of Bax(NH3)Fe2Se2, compared with β-FeSe, suggests an unchanged intra- Fe2Se2-layer structure and the Tc enhancement is due to a 3D to 2D-like Fermi surface transformation. The superconducting coherent lengths (0), the Ginzburg-Landau parameters κ and penetration depths (0) obtained from the extrapolated lower and upper critical fields Bc1 (0) and Bc2 (0) indicate that both compounds are typical type-II superconductors. The temperature dependence of 1/l2(T) of Bax(NH3)Fe2Se2 deduced from the low-field magnetic susceptibility shows a twogap s-wave behavior with superconducting gaps of δ1 = 6.47 meV and δ2= 1.06 meV.

AB - Superconducting properties were studied on high quality superconductors Bax(NH3)Fe2Se2 (Tc= 39 K) and Srx(NH3)Fe2Se2 (Tc = 44 K) prepared by intercalating Ba/Sr atoms into tetragonal β-FeSe by liquid ammonia. The elongated c-axis and almost unchanged a-axis of Bax(NH3)Fe2Se2, compared with β-FeSe, suggests an unchanged intra- Fe2Se2-layer structure and the Tc enhancement is due to a 3D to 2D-like Fermi surface transformation. The superconducting coherent lengths (0), the Ginzburg-Landau parameters κ and penetration depths (0) obtained from the extrapolated lower and upper critical fields Bc1 (0) and Bc2 (0) indicate that both compounds are typical type-II superconductors. The temperature dependence of 1/l2(T) of Bax(NH3)Fe2Se2 deduced from the low-field magnetic susceptibility shows a twogap s-wave behavior with superconducting gaps of δ1 = 6.47 meV and δ2= 1.06 meV.

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KW - penetration depth

KW - two-gap s-wave superconductor

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