Strain induced superconductivity in the parent compound BaFe2As2

• Published in: Nature communications Vol. 4; no. 1; p. 2877
• Main Authors: Engelmann, J., Grinenko, V., Chekhonin, P., Skrotzki, W., Efremov, D.V., Oswald, S., Iida, K., Hühne, R., Hänisch, J., Hoffmann, M., Kurth, F., Schultz, L., Holzapfel, B.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06-12-2013; Nature Publishing Group
• Subjects: 639/301/119/1003; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms3877

The discovery of superconductivity with a transition temperature,
T
c
, up to 65 K in single-layer FeSe (bulk
T
c
=8 K) films grown on SrTiO
3
substrates has attracted special attention to Fe-based thin films. The high
T
c
is a consequence of the combined effect of electron transfer from the oxygen-vacant substrate to the FeSe thin film and lattice tensile strain. Here we demonstrate the realization of superconductivity in the parent compound BaFe
2
As
2
(no bulk
T
c
) just by tensile lattice strain without charge doping. We investigate the interplay between strain and superconductivity in epitaxial BaFe
2
As
2
thin films on Fe-buffered MgAl
2
O
4
single crystalline substrates. The strong interfacial bonding between Fe and the FeAs sublattice increases the Fe–Fe distance due to the lattice misfit, which leads to a suppression of the antiferromagnetic spin density wave and induces superconductivity with bulk
T
c
≈10 K. These results highlight the role of structural changes in controlling the phase diagram of Fe-based superconductors.
It is well known that strain can modify the critical temperature below which a material becomes superconducting. Engelmann
et al.
show that strain does not just modify the critical temperature of iron pnictides but can induce superconductivity in the otherwise non-superconducting undoped phase of BaFe
2
As
2
.