No evidence of the crossover in the spin fluctuations of Ca(Fe<sub>1-<i>x</i></sub>Co<i><sub>x</sub></i>)<sub>2</sub>As<sub>2 </sub>and unusual suppression with temperature for <i>x</i> = 0.030.
ORAL
Abstract
In the Ca(Fe1-xCox)2As2 family, the superconductivity appears with Co doping after a first-order suppression of an antiferromagnetic order. Here, we present results of our inelastic neutron scattering measurement on Ca(Fe1-xCox)2As2, x=0.026 (antiferromagnetically ordered below TN=64±7 K) and x=0.030 (superconducting below Tc=14.6±1 K). Our results suggest that, unlike Ba(Fe1-xCox)2As2, smooth evolution of the gapped spin waves to diffusive spin fluctuations is absent in Ca(Fe1-xCox)2As2 and the result is consistent with the first order phase transition from magnetically ordered to superconducting state. Additionally, we observed an unusual suppression of the spin fluctuations with decreasing temperature for x=0.030, possibly arising due to compound’s proximity to the collapsed tetragonal phase.
*Work at the Ames Laboratory was supported by US DOE, Basic Energy Sciences, Division of Material Sciences and Engineering, under contract No. DE-AC02-07CH11358. This research used resources of SNS, a DOE office of science user facility operated by ORNL.
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Presenters
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Aashish Sapkota
- Ames Laboratory, Iowa State University
- Dept. of Physics and Astronomy, Ames Laboratory/Iowa State University
- Dept. of Physics, Iowa State Univ