Volume 84, Number 3, November 2008
Article Number 37002
Number of page(s) 4
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 17 October 2008
EPL, 84 (2008) 37002
DOI: 10.1209/0295-5075/84/37002

Tellurium substitution effect on superconductivity of the$\alpha$-phase iron selenide

Kuo-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.

© EPLA 2008