Superconducting phases in (NH3)yMxFeSe1zTez (M=Li,Na,andCa)

Yusuke Sakai, Lu Zheng, Masanari Izumi, Kazuya Teranishi, Ritsuko Eguchi, Hidenori Goto, Taiki Onji, Shingo Araki, Tatsuo C. Kobayashi, and Yoshihiro Kubozono
Phys. Rev. B 89, 144509 – Published 21 April 2014
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Abstract

Superconducting phases of (NH3)yMxFeSe1zTez have been synthesized by the intercalation of metal atoms (M:Li,Na,Ca) into FeSe and FeSe0.5Te0.5 using a low-temperature liquid NH3 technique. The superconducting transition temperature (Tc) is 31.5 K for Na-doped FeSe, and for Li-, Na-, and Ca-doped FeSe0.5Te0.5 it is 26, 22, and 17 K, respectively. The 31.5 K superconducting is the superconducting phase in ammoniated Na-doped FeSe. The Tc is lower than that (onset Tc=46K) of the superconducting phase reported previously. The reason why the Tc of this phase is lower is discussed based on the structure. The pressure dependences of Tc in the (NH3)yNa0.5FeSe and (NH3)yNa0.4FeSe0.5Te0.5 samples have been measured and a negative pressure dependence is observed; i.e., a decrease in lattice constant c leads to a decrease in Tc, consistent with the behavior of (NH3)yCs0.4FeSe reported previously by our group. Furthermore, the magnetic behavior of (NH3)yNa0.4FeSe0.5Te0.5 has been fully investigated at different applied magnetic fields (H) to determine the critical magnetic field. This is a successful metal intercalation into FeSe1zTez (z0) and an observation of superconductivity.

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  • Received 4 February 2014
  • Revised 1 April 2014

DOI:https://doi.org/10.1103/PhysRevB.89.144509

©2014 American Physical Society

Authors & Affiliations

Yusuke Sakai1, Lu Zheng1, Masanari Izumi1, Kazuya Teranishi1, Ritsuko Eguchi1, Hidenori Goto1, Taiki Onji2, Shingo Araki2, Tatsuo C. Kobayashi2,3, and Yoshihiro Kubozono1,3,*

  • 1Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan
  • 2Department of Physics, Okayama University, Okayama 700-8530, Japan
  • 3Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530, Japan

  • *kubozono@cc.okayama-u.ac.jp

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Issue

Vol. 89, Iss. 14 — 1 April 2014

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