Temperature-Dependent Transformation of the Magnetic Excitation Spectrum on Approaching Superconductivity in Fe1+yx(Ni/Cu)xTe0.5Se0.5

Zhijun Xu, Jinsheng Wen, Yang Zhao, Masaaki Matsuda, Wei Ku, Xuerong Liu, Genda Gu, D.-H. Lee, R. J. Birgeneau, J. M. Tranquada, and Guangyong Xu
Phys. Rev. Lett. 109, 227002 – Published 28 November 2012

Abstract

Spin excitations are one of the top candidates for mediating electron pairing in unconventional superconductors. Their coupling to superconductivity is evident in a large number of systems, by the observation of an abrupt redistribution of magnetic spectral weight at the superconducting transition temperature, Tc, for energies comparable to the superconducting gap. Here we report inelastic neutron scattering measurements on Fe-based superconductors, Fe1x(Ni/Cu)xTe0.5Se0.5, that emphasize an additional signature. The overall shape of the low energy magnetic dispersion changes from two incommensurate vertical columns at TTc to a distinctly different U-shaped dispersion at low temperature. Importantly, this spectral reconstruction is apparent for temperatures up to 3Tc. If the magnetic excitations are involved in the pairing mechanism, their surprising modification on the approach to Tc demonstrates that strong interactions are involved.

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  • Received 20 January 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.227002

© 2012 American Physical Society

Authors & Affiliations

Zhijun Xu1, Jinsheng Wen1,2,3, Yang Zhao4,5, Masaaki Matsuda6, Wei Ku1, Xuerong Liu1, Genda Gu1, D.-H. Lee2,3, R. J. Birgeneau2,3, J. M. Tranquada1, and Guangyong Xu1

  • 1Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
  • 2Physics Department, University of California, Berkeley, California 94720, USA
  • 3Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 4NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
  • 5Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
  • 6Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

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Issue

Vol. 109, Iss. 22 — 30 November 2012

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