Competing superconducting and magnetic order parameters and field-induced magnetism in electron-doped $\mathrm{Ba}{({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x})}_{2}{\mathrm{As}}_{2}$

Larsen, J.; Mencia Uranga, B.; Stieper, G.; Holm, S. L.; Bernhard, Christian; Wolf, T.; Lefmann, K.; Andersen, B. M.; Niedermayer, Christof

doi:10.1103/PhysRevB.91.024504

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Journal article

Competing superconducting and magnetic order parameters and field-induced magnetism in electron-doped $\mathrm{Ba}{({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x})}_{2}{\mathrm{As}}_{2}$

Larsen, J. Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark
Mencia Uranga, B. Niels Bohr Institute, University of Copenhagen, Denmark
Stieper, G. Niels Bohr Institute, University of Copenhagen, Denmark
Holm, S. L. Niels Bohr Institute, University of Copenhagen, Denmark - Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, Villigen, Switzerland
Bernhard, Christian University of Fribourg, Department of Physics and Fribourg Centre for Nanomaterials, Switzerland
Wolf, T. Karlsruher Institut für Technologie, Institut für Festkörperphysik, Germany
Lefmann, K. Niels Bohr Institute, University of Copenhagen, Denmark
Andersen, B. M. Niels Bohr Institute, University of Copenhagen, Denmark
Niedermayer, Christof Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, Villigen, Switzerland

13.01.2015

Published in:

Physical Review B. - 2015, vol. 91, no. 2, p. 024504

English We have studied the magnetic and superconducting properties of Ba(Fe0.95Co0.05)2As2 as a function of temperature and external magnetic field using neutron scattering and muon spin rotation. Below the superconducting transition temperature the magnetic and superconducting order parameters coexist and compete. A magnetic field can significantly enhance the magnetic scattering in the superconducting state, roughly doubling the Bragg intensity at 13.5 T. We perform a microscopic modeling of the data by use of a five-band Hamiltonian relevant to iron pnictides. In the superconducting state, vortices can slow down and freeze spin fluctuations locally. When such regions couple they result in a long-range ordered antiferromagnetic phase producing the enhanced magnetic elastic scattering in agreement with experiments.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

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