Neutron-Scattering Measurements of Spin Excitations in LaFeAsO and Ba(Fe0.953Co0.047)2As2: Evidence for a Sharp Enhancement of Spin Fluctuations by Nematic Order

Published

February 4, 2015

Author(s)

Qiang Zhang, Rafael M. Fernandes, Jagat Lamsal, Jiaqiang Yan, Songxue Chi, Gregory S. Tucker, Daniel K. Pratt, Jeffrey W. Lynn, R. W. McCallum, P. C. Canfield, Thomas A. Lograsso, Alan Goldman, David Vaknin, Robert J. McQueeney

Abstract

Inelastic neutron scattering was employed to investigate the impact of electronic nematic order on the magnetic spectra of LaFeAsO and Ba(Fe_0.9536Cod0.047)₂As₂. These materials are ideal to study the paramagnetic-nematic state, since the nematic order, signaled by the tetragonal-to-orthorhombic transition at the temperature T_s, sets in well above the stripe antiferromagnetic ordering temperature T_N. We find in both systems that the temperature-dependent dynamic susceptibility displays an anomaly at T_S followed by a sharp enhancement in the spin-spin correlation length, revealing a strong feedback effect of nematic order on the low-energy magnetic spectrum. Our findings can be consistently described by a model that attributes the structural/nematic transition to magnetic fluctuations, and unveils the key role played by nematic order in promoting the long-range stripe antiferromagnetic order in pnictides.

Citation

Physical Review Letters

Volume

114

Issue

6

Pub Type

Journals

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Keywords

Superconductor, correlated electrons, magnetic correlations, inelastic neutron scattering, nematic order, dynamic correlation range, iron superconductor

Citation

Zhang, Q. , Fernandes, R. , Lamsal, J. , Yan, J. , Chi, S. , Tucker, G. , Pratt, D. , Lynn, J. , McCallum, R. , Canfield, P. , Lograsso, T. , Goldman, A. , Vaknin, D. and McQueeney, R. (2015), Neutron-Scattering Measurements of Spin Excitations in LaFeAsO and Ba(Fe_0.953Co_0.047)₂As₂: Evidence for a Sharp Enhancement of Spin Fluctuations by Nematic Order, Physical Review Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917130 (Accessed December 10, 2024)