Electron doping evolution of the magnetic excitations in BaFe2xNixAs2

Huiqian Luo, Xingye Lu, Rui Zhang, Meng Wang, E. A. Goremychkin, D. T. Adroja, Sergey Danilkin, Guochu Deng, Zahra Yamani, and Pengcheng Dai
Phys. Rev. B 88, 144516 – Published 25 October 2013

Abstract

We use inelastic neutron scattering (INS) spectroscopy to study the magnetic excitations spectra throughout the Brillouin zone in electron-doped iron pnictide superconductors BaFe2xNixAs2 with x=0.096,0.15,0.18. While the x=0.096 sample is near optimal superconductivity with Tc=20 K and has coexisting static incommensurate magnetic order, the x=0.15,0.18 samples are electron overdoped with reduced Tc of 14 and 8 K, respectively, and have no static antiferromagnetic (AF) order. In previous INS work on undoped (x=0) and electron optimally doped (x=0.1) samples, the effect of electron doping was found to modify spin waves in the parent compound BaFe2As2 below 100 meV and induce a neutron spin resonance at the commensurate AF ordering wave vector that couples with superconductivity. While the new data collected on the x=0.096 sample confirm the overall features of the earlier work, our careful temperature dependent study of the resonance reveals that the resonance suddenly changes its Q width below Tc similar to that of the optimally hole-doped iron pnictides Ba0.67K0.33Fe2As2. In addition, we establish the dispersion of the resonance and find it to change from commensurate to transversely incommensurate with increasing energy. Upon further electron doping to overdoped iron pnictides with x=0.15 and 0.18, the resonance becomes weaker and transversely incommensurate at all energies, while spin excitations above 100 meV are still not much affected. Our absolute spin excitation intensity measurements throughout the Brillouin zone for x=0.096,0.15,0.18 confirm the notion that the low-energy spin excitation coupling with itinerant electron is important for superconductivity in these materials, even though the high-energy spin excitations are weakly doping dependent.

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  • Received 14 August 2013

DOI:https://doi.org/10.1103/PhysRevB.88.144516

©2013 American Physical Society

Authors & Affiliations

Huiqian Luo1,*, Xingye Lu1,*, Rui Zhang1, Meng Wang1, E. A. Goremychkin2, D. T. Adroja2, Sergey Danilkin3, Guochu Deng3, Zahra Yamani4, and Pengcheng Dai5,1,†

  • 1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 2ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, United Kingdom
  • 3Bragg Institute, Australian Nuclear Science and Technology Organization, New Illawarra Road, Lucas Heights NSW-2234, Australia
  • 4Canadian Neutron Beam Centre, National Research Council, Chalk River Laboratories, Chalk River, Ontario K0J 1J0, Canada
  • 5Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA

  • *These authors made equal contributions to this paper.
  • pdai@rice.edu

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Vol. 88, Iss. 14 — 1 October 2013

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