Interplay between lattice and spin states degree of freedom in the FeSe superconductor: dynamic spin state instabilities

  title={Interplay between lattice and spin states degree of freedom in the FeSe superconductor: dynamic spin state instabilities},
  author={Vladimir Gnezdilov and Yu. Pashkevich and Peter Lemmens and Dirk Wulferding and T. V. Shevtsova and Alexandr Gusev and Dmitry A. Chareev and Alexander N. Vasiliev},
  journal={Physical Review B},
Polarized Raman-scattering spectra of superconducting, single-crystalline FeSe evidence pronounced phonon anomalies with temperature reduction. A large ($\ensuremath{\sim}6.5%$) hardening of the ${B}_{1g}$(Fe) phonon mode is attributed to the suppression of local fluctuations of the iron spin state with a gradual decrease of the iron paramagnetic moment. Ab initio lattice dynamic calculations support this conclusion. The enhancement of the low-frequency spectral weight above the structural… 

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