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Durham University

Department of Physics

Staff profile

Publication details for Professor Tom Lancaster

Burrard-Lucas, Maththew, Free, David G., Sedlmaier, Stefan J. Wright, Jack D., Cassidy, Simon J., Hara, Yoshiaki Corkett, Alex J. Lancaster, Tom, Baker, Peter J. Blundell, Stephen J. & Clarke, Simon J. (2013). Enhancement of the superconducting transition temperature of FeSe by intercalation of a molecular spacer layer. Nature Materials 12(1): 15-19.

Author(s) from Durham


The discovery of high-temperature superconductivity in a
layered iron arsenide1 has led to an intensive search to optimize
the superconducting properties of iron-based superconductors
by changing the chemical composition of the spacer layer
between adjacent anionic iron arsenide layers2–7. Superconductivity
has been found in iron arsenides with cationic spacer
layers consisting of metal ions (for example, LiC, NaC, KC, Ba2C)
or PbO- or perovskite-type oxide layers, and also in Fe1:01Se
(ref. 8) with neutral layers similar in structure to those found
in the iron arsenides and no spacer layer. Here we demonstrate
the synthesis of Lix(NH2)y(NH3)1􀀀yFe2Se2 (x  0:6; y  0:2),
with lithium ions, lithium amide and ammonia acting as the
spacer layer between FeSe layers, which exhibits superconductivity
at 43(1) K, higher than in any FeSe-derived compound
reported so far. We have determined the crystal structure
using neutron powder diffraction and used magnetometry and
muon-spin rotation data to determine the superconducting
properties. This new synthetic route opens up the possibility
of further exploitation of related molecular intercalations in
this and other systems to greatly optimize the superconducting
properties in this family.