# 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
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
Language
• English
Classification
Physics