Neutron spectroscopy is used to investigate the magnetic fluctuations in ${\mathrm{Fe}}_{1+x}\mathrm{Te}$—a parent compound of chalcogenide superconductors. Incommensurate “stripelike” excitations soften with increased interstitial iron concentration. The energy crossover from incommensurate to stripy fluctuations defines an apparent hourglass dispersion. Application of sum rules of neutron scattering find that the integrated intensity is inconsistent with an $S=1{\mathrm{Fe}}^{2+}$ ground state and significantly less than $S=2$ predicted from weak crystal field arguments pointing towards the ${\mathrm{Fe}}^{2+}$ being in a superposition of orbital states. The results suggest that a highly anisotropic order competes with superconductivity in chalcogenide systems.

• Received 6 January 2014
• Revised 9 September 2014

DOI:https://doi.org/10.1103/PhysRevB.90.121113