Journal
PHYSICAL REVIEW B
Volume 86, Issue 24, Pages -Publisher
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.86.245113
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Funding
- Center for Emergent Superconductivity, a DOE Energy Frontier Research Center [DE-AC0298CH1088]
- NSF [1066293]
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [1104909] Funding Source: National Science Foundation
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We study the influence of quantum fluctuations on the electron self-energy in the normal state of iron pnictide superconductors using a five-orbital tight-binding model with generalized Hubbard on-site interactions. Within a one-loop treatment, we find that an overdamped collective mode develops at low frequency in channels associated with quasi-one-dimensional d(xz) and d(yz) bands. When the critical point for the C-4-symmetry-broken phase (structural phase transition) is approached, the overdamped collective modes soften, and acquire increased spectral weight, resulting in non-Fermi-liquid behavior at the Fermi surface characterized by a frequency dependence of the imaginary part of the electron self-energy of the form. omega(lambda), 0 < lambda < 1. We argue that this non-Fermi-liquid behavior is responsible for the recently observed zero-bias enhancement in the tunneling signal in point-contact spectroscopy. A key experimental test of this proposal is the absence of non-Fermi-liquid behavior in the hole-doped materials. Our result suggests that quantum criticality plays an important role in understanding the normal-state properties of iron pnictide superconductors. DOI: 10.1103/PhysRevB.86.245113
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