Preparation of new superconductors by metal doping of two-dimensional layered materials using ethylenediamine

Xiao Miao; Takahiro Terao; Xiaofan Yang; Saki Nishiyama; Takafumi Miyazaki; Hidenori Goto; Yoshihiro Iwasa; Yoshihiro Kubozono

doi:10.1103/PhysRevB.96.014502

Preparation of new superconductors by metal doping of two-dimensional layered materials using ethylenediamine

Xiao Miao, Takahiro Terao, Xiaofan Yang, Saki Nishiyama, Takafumi Miyazaki, Hidenori Goto, Yoshihiro Iwasa, Yoshihiro Kubozono

DOI 10.1103/PhysRevB.96.014502 · Physical Review B

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Abstract

We have studied new superconductors prepared by metal doping of two-dimensional (2D) layered materials, FeSe and FeSe0.5Te0.5, using ethylenediamine (EDA). The superconducting transition temperatures (Tcs) of metal-doped FeSe and metal-doped FeSe0.5Te0.5, i.e., (EDA)yMxFeSe and (EDA)yMxFeSe0.5Te0.5 (M: Li, Na, and K), were 31–45 K and 19–25 K, respectively. The stoichiometry of each sample was clarified by energy dispersive x-ray (EDX) spectroscopy, and the x-ray powder diffraction pattern indicated a large expansion of lattice constant c, indicating the cointercalation of metal atoms and EDA. The pressure dependence of superconductivity in (EDA)yNaxFeSe0.5Te0.5 has been investigated at a pressure of 0–0.8GPa, showing negative pressure dependence in the same manner as (NH3)yNaxFeSe0.5Te0.5. The Tc−c phase diagrams of MxFeSe and MxFeSe0.5Te0.5 were drawn afresh from the Tc and c of (EDA)yMxFeSe and (EDA)yMxFeSe0.5Te0.5, showing that the Tc increases with increasing c but that extreme expansion of c reverses the Tc trend.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
(EDA)yLixFe0.976Se Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	45	Pressure not reported	midpoint
(EDA)yNa0.820Fe0.765Se Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	43	Pressure not reported	midpoint
(EDA)yLixFe0.8741Se0.4598Te0.54 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	22.5	Pressure not reported	midpoint
(EDA)yNa0.8Fe0.88Se0.518Te0.482 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	25	Pressure not reported	midpoint
(EDA)yNa0.8Fe0.87Se0.51Te0.49 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	22	Pressure not reported	midpoint
(EDA)yK1.17Fe0.83Se0.523Te0.477 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	19	Pressure not reported	midpoint
(EDA)yNa0.6Fe0.85Se0.53Te0.47 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	24	Pressure unresolved	midpoint
Fe0.867Se Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	9	Pressure not reported	unknown
Fe0.852Se0.547Te0.45 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	14	Pressure not reported	unknown