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arXiv · 1407.0568

Short-range cluster spin glass near optimal superconductivity in BaFe$_{2-x}$Ni$_{x}$As$_{2}$

Xingye Lu·David W. Tam·Chenglin Zhang·Huiqian Luo·Meng Wang·Rui Zhang·Leland W. Harriger·T. Keller·B. Keimer·L. -P. Regnault·Thomas A. Maier·Pengcheng Dai
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Abstract

High-temperature superconductivity in iron pnictides occurs when electrons are doped into their antiferromagnetic (AF) parent compounds. In addition to inducing superconductivity, electron-doping also changes the static commensurate AF order in the undoped parent compounds into short-range incommensurate AF order near optimal superconductivity. Here we use neutron scattering to demonstrate that the incommensurate AF order in BaFe$_{2-x}$Ni$_{x}$As$_{2}$ is not a spin-density-wave arising from the itinerant electrons in nested Fermi surfaces, but consistent with a cluster spin glass in the matrix of the superconducting phase. Therefore, optimal superconductivity in iron pnictides coexists and competes with a mesoscopically separated cluster spin glass phase, much different from the homogeneous coexisting AF and superconducting phases in the underdoped regime.

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Xingye Lu, David W. Tam, Chenglin Zhang, Huiqian Luo, Meng Wang, Rui Zhang, Leland W. Harriger, T. Keller, B. Keimer, L. -P. Regnault, Thomas A. Maier, Pengcheng Dai. 2014-07-02. Short-range cluster spin glass near optimal superconductivity in BaFe$_{2-x}$Ni$_{x}$As$_{2}$. https://doi.org/10.1103/physrevb.90.024509

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