Superconductivity in the PbO-type structure alpha-FeSe.
The recent discovery of superconductivity with relatively high transition temperature (Tc) in the layered iron-based quaternary oxypnictides La[O(1-x)F(x)] FeAs by Kamihara et al. [Kamihara Y, Watanabe T, Hirano M, Hosono H (2008) Iron-based layered superconductor La[O1-xFx] FeAs (x = 0.05-0.12) with Tc = 26 K. J Am Chem Soc 130:3296-3297.] was a real surprise and has generated tremendous interest. Although superconductivity exists in alloy that contains the element Fe, LaOMPn (with M = Fe, Ni; and Pn = P and As) is the first system where Fe plays the key role to the occurrence of superconductivity. LaOMPn has a layered crystal structure with an Fe-based plane. It is quite natural to search whether there exists other Fe based planar compounds that exhibit superconductivity. Here, we report the observation of superconductivity with zero-resistance transition temperature at 8 K in the PbO-type alpha-FeSe compound. A key observation is that the clean superconducting phase exists only in those samples prepared with intentional Se deficiency. FeSe, compared with LaOFeAs, is less toxic and much easier to handle. What is truly striking is that this compound has the same, perhaps simpler, planar crystal sublattice as the layered oxypnictides. Therefore, this result provides an opportunity to better understand the underlying mechanism of superconductivity in this class of unconventional superconductors.
Hsu
Fong-Chi
FC
Institute of Physics, Academia Sinica, Nankang, Taipei 115, Taiwan.
Luo
Jiu-Yong
JY
Yeh
Kuo-Wei
KW
Chen
Ta-Kun
TK
Huang
Tzu-Wen
TW
Wu
Phillip M
PM
Lee
Yong-Chi
YC
Huang
Yi-Lin
YL
Chu
Yan-Yi
YY
Yan
Der-Chung
DC
Wu
Maw-Kuen
MK
J Am Chem Soc. 2008 Mar 19;130(11):3296-7
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