Spin anisotropy of the resonance peak in superconducting FeSe${}_{0.5}$Te${}_{0.5}$

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Spin anisotropy of the resonance peak in superconducting FeSe $_{0.5}$ Te $_{0.5}$

P. Babkevich, B. Roessli, S. N. Gvasaliya, L.-P. Regnault, P. G. Freeman, E. Pomjakushina, K. Conder, and A. T. Boothroyd

Phys. Rev. B 83, 180506(R) – Published 25 May 2011

Abstract

We have used polarized-neutron inelastic scattering to resolve the spin fluctuations in superconducting FeSe $_{0.5}$ Te $_{0.5}$ into components parallel and perpendicular to the layers. A spin resonance at an energy of 6.5 meV is observed to develop below $T_{c}$ in both fluctuation components. The resonance peak is anisotropic, with the in-plane component slightly larger than the out-of-plane component. Away from the resonance peak, the magnetic fluctuations are isotropic in the energy range studied. The results are consistent with a dominant singlet pairing state with $s^{\pm}$ symmetry, with a possible minority component of different symmetry.

Received 14 April 2011

DOI:https://doi.org/10.1103/PhysRevB.83.180506

Authors & Affiliations

P. Babkevich^1,2,*, B. Roessli², S. N. Gvasaliya^3,†, L.-P. Regnault⁴, P. G. Freeman⁵, E. Pomjakushina⁶, K. Conder⁶, and A. T. Boothroyd¹

¹Department of Physics, Oxford University, Oxford, OX1 3PU, United Kingdom
²Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
³Institute for Solid State Physics, ETH Zürich, Zürich CH-8093, Switzerland
⁴SPSMS, UMR-E9001, CEA/UJF-Grenoble 1, MDN, 17 rue des Martyrs, FR-38054 Grenoble Cedex 9, France
⁵Institut Laue-Langevin, BP 156, FR-38042 Grenoble Cedex 9, France
⁶Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland

^*peter.babkevich@physics.ox.ac.uk
^†Previous address: Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.

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Vol. 83, Iss. 18 — 1 May 2011

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