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Justin Panarin

Spin dynamics of the unconventional superconductor CeCoIn5

Published on 5 April 2012
Thesis presented April 05, 2012

In this thesis, the spin dynamics of CeCoIn5 has been studied by inelastic neutron scattering. CeCoIn5 presents the highest critical temperature (Tc = 2.3 K) among heavy fermion Ce-based compounds and shows an unconventional superconductivity with a d{x2-y2}-wave gap. The magnetic excitation spectra is radically changed in the superconducting state with the apparition of an intense excitation named "Spin resonance". This kind of excitation has already been discovered in high-Tc superconductors and even in the new Iron-based superconductors. In this thesis, we focused on the evolution of the spin resonance with the application of a magnetic field and the introduction of magnetic and non-magnetic impurities. From our study, the main effect of impurities is to decrease the superconducting gap which leads to a proportional decrease of the resonance energy. The case of magnetic field is more difficult and our research suggest a Zeeman splitting of the spin resonance in agreements with the models developed for the cuprates.

Heavy fermion, CeCoIn5, Unconventional superconductivity, Spin resonance, Inelastic neutron scattering

On-line thesis.