Publication Type
Journal
Journal Name
Physical Review Letters
Publication Date
Page Number
227002
Volume
111
Issue
22
Abstract
The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central
topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the
absence of magnetic fluctuations in the non-superconducting collapsed tetragonal phase of CaFe2As2 via inelas-
tic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary
ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetrag-
onal phase of CaFe2As2 is non-magnetic, and discuss this result in light of recent reports of high-temperature
superconductivity in the collapsed tetragonal phase of closely related compounds.
