Tellurium substitution effect on superconductivity of the-phase iron selenideKuo-Wei Yeh1, Tzu-Wen Huang1, Yi-lin Huang1, Ta-Kun Chen1, Fong-Chi Hsu1, 2, Phillip M. Wu3, Yong-Chi Lee1, Yan-Yi Chu1, 2, Chi-Lian Chen1, Jiu-Yong Luo1, Der-Chung Yan1 and Maw-Kuen Wu1
1 Institute of Physics, Academia Sinica - Nankang, Taipei, Taiwan
2 Department of Materials Science and Engineering, National Tsing Hua University - Hsinchu, Taiwan
3 Department of Physics, Duke University - Durham, NC, USA
received 6 August 2008; accepted in final form 15 September 2008; published November 2008
published online 17 October 2008
We have carried out a systematic study of the PbO-type compound FeSe1-xTex (x = 0 – 1), where the Te substitution effect on superconductivity is investigated. It is found that the superconducting transition temperature reaches a maximum of Tc=15.2 K at about 50% Te substitution. The pressure-enhanced Tc of FeSe0.5Te0.5 is more than 10 times larger than that of FeSe. Interestingly, FeTe is no longer superconducting. A low-temperature structural distortion changes FeTe from triclinic symmetry to orthorhombic symmetry. We believe that this structural change breaks the magnetic symmetry and suppresses superconductivity in FeTe.
74.62.Dh - Effects of crystal defects, doping and substitution.
74.70.Dd - Ternary, quaternary, and multinary compounds (including Chevrel phases, borocarbides, etc.).
74.62.Fj - Pressure effects.
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