Scanning tunneling microscopy and spectroscopy on iron-pnictides

Yin, Yi; Zech, Martin; Williams, Tess; Hoffman, Jennifer

doi:10.1016/j.physc.2009.03.053

Cited by 44 publications

(38 citation statements)

References 71 publications

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“…An evidence for the pseudogap has been reported from photoemission experiments on polycrystalline samples (e.g., see [142,143]) and in some ARPES experiments on single crystals [144], but this is supported neither by other numerous ARPES studies [41,42,57,59,64,145,146] nor by STM measurements [147,148]. The absence of the pseudogap in ARPES spectra may be just a consequence of low spectral weight modulation by the magnetic ordering that may question its importance for superconductivity, discussed in previous section.…”

Section: Pseudogapmentioning

confidence: 94%

Iron-based superconductors: Magnetism, superconductivity, and electronic structure (Review Article)

Kordyuk

2012

Low Temperature Physics

218

155

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Angle resolved photoemission spectroscopy (ARPES) reveals the features of the electronic structure of quasitwo-dimensional crystals, which are crucial for the formation of spin and charge ordering and determine the mechanisms of electron-electron interaction, including the superconducting pairing. The newly discovered ironbased superconductors (FeSC) promise interesting physics that stems, on one hand, from a coexistence of superconductivity and magnetism and, on the other hand, from complex multi-band electronic structure. In this review I want to give a simple introduction to the FeSC physics, and to advocate an opinion that all the complexity of FeSC properties is encapsulated in their electronic structure. For many compounds, this structure was determined in numerous ARPES experiments and agrees reasonably well with the results of band structure calculations. Nevertheless, the existing small differences may help to understand the mechanisms of the magnetic ordering and superconducting pairing in FeSC.

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Section: Pseudogapmentioning

confidence: 94%

Iron-based superconductors: Magnetism, superconductivity, and electronic structure (Review Article)

Kordyuk

2012

Low Temperature Physics

218

155

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“…Despite of that the local gaps measured by STM [11][12][13][14] do not change very drastically. This makes the inter-orbital pairing with repulsive U 12 and thus s ± -superconducting state [9] rather unlikely.…”

Section: Discussionmentioning

confidence: 86%

“…It is interesting to note that similarly as in high temperature superconductors, the scanning tunnelling microscopy (STM) measurements reveal nanoscale inhomogeneities in iron oxypnictides. The superconducting gap magnitude varies by about ±20% in the doped samples [11][12][13][14]. * corresponding author; e-mail: karol@tytan.umcs.lublin.pl…”

Section: Introductionmentioning

confidence: 99%

Inter-Orbital Effects in the Impure Pnictide Superconductors

Ciechan

Wysokiński

2010

Acta Phys. Pol. A

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We study the local properties of the iron oxypnictides by means of the real space Bogolubov-de Gennes equations. Starting with the realistic energy spectrum and assuming small amount of impurities we calculate the energy dependence of the local density of states and spatial distribution of the local values of the superconducting energy gap. We pay particular attention to the role of the inter-orbital scattering of pairs and the effect of impurity scattering on the superconducting state. The effect of inter-orbital impurities depends on the relative signs of the order parameters related to two orbitals in question. For opposite signs impurities produce bound states inside the gap, while for the same sign of the order parameters they hardly affect the superconductor. The results obtained for impure systems have been shown as maps of the order parameters and local density of states. They well compare with the existing scanning tunnelling microscopy spectra of the iron pnictides.

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“…However, a highly anisotropic material can be easily identified by the tendency of vortices to pin on impurities in the surface layer, thus signifying their ease of bending or even their separation into individual ''pancake'' vortices. 148 For example, Ba(Fe 1Àx Co x ) 2 As 2 is found to be a relatively isotropic superconductor, as the vortex tops are uncorrelated with a set of surface defects which clearly independently destroy local superconductivity. 149 In contrast, Bi-2212 is found to be a highly anisotropic superconductor, in which the majority of vortex tops appear pinned by surface Zn impurities.…”

Section: Chemical Disorder and Vortex Pinningmentioning

confidence: 99%

Interplay of chemical disorder and electronic inhomogeneity in unconventional superconductors

Zeljkovic

Hoffman

2013

Phys. Chem. Chem. Phys.

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Many of today's forefront materials, such as high-T c superconductors, doped semiconductors, and colossal magnetoresistance materials, are structurally, chemically and/or electronically inhomogeneous at the nanoscale. Although inhomogeneity can degrade the utility of some materials, defects can also be advantageous. Quite generally, defects can serve as nanoscale probes and facilitate quasiparticle scattering used to extract otherwise inaccessible electronic properties. In superconductors, nonstoichiometric dopants are typically necessary to achieve a high transition temperature, while both structural and chemical defects are used to pin vortices and increase critical current. Scanning tunneling microscopy (STM) has proven to be an ideal technique for studying these processes at the atomic scale.In this perspective, we present an overview of STM studies on chemical disorder in unconventional superconductors, and discuss how dopants, impurities and adatoms may be used to probe, pin or enhance the intrinsic electronic properties of these materials.

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Scanning tunneling microscopy and spectroscopy on iron-pnictides

Cited by 44 publications

References 71 publications

Iron-based superconductors: Magnetism, superconductivity, and electronic structure (Review Article)

Iron-based superconductors: Magnetism, superconductivity, and electronic structure (Review Article)

Inter-Orbital Effects in the Impure Pnictide Superconductors

Interplay of chemical disorder and electronic inhomogeneity in unconventional superconductors

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