Pressure induced evolution of superconductivity and magnetic hourglass dispersion in Fe1.02Te0.7Se0.3

Iron based high temperature superconductors have several common features with superconducting cuprates, including the square lattice and the proximity to an antiferromagnetic phase. Themagnetic excitation spectrumbelowTc of Fe Te Se 1.02 0.7 0.3 shows an hourglass-shaped dispersionwith a resonance around the commensurate point . In a previous inelastic neutron scattering study, we showed that the hourglass-shaped dispersion ismost likely a prerequisite for superconductivity, while the consequences are the opening of a gap and a shift of spectral weight. In this paper we follow the evolution of the hourglass shaped dispersion under applied pressure up to 12 kbar. Our results show that that the pressure-induced 37% increase ofTc is concomitant with a change in themagnetic excitation spectrum,with an increase of the hourglass energy by 38%.