Nematic Electronic Structure in the "Parent" State of the Iron-Based Superconductor Ca(Fe1-xCox)(2)As-2

TitleNematic Electronic Structure in the "Parent" State of the Iron-Based Superconductor Ca(Fe1-xCox)(2)As-2
Publication TypeJournal Article
Year of Publication2010
AuthorsChuang TM, Allan MP, Lee J, Xie Y, Ni N, Bud'ko SL, Boebinger GS, Canfield PC, Davis JC
Journal TitleScience
Volume327
Pages181-184
Date Published01/08
ISBN Number0036-8075
Accession NumberISI:000273394000028
Keywordsmott insulator, phases
Abstract

The mechanism of high-temperature superconductivity in the newly discovered iron-based superconductors is unresolved. We use spectroscopic imaging-scanning tunneling microscopy to study the electronic structure of a representative compound CaFe1.94Co0.06As2 in the "parent" state from which this superconductivity emerges. Static, unidirectional electronic nanostructures of dimension eight times the inter-iron-atom distance a(Fe-Fe) and aligned along the crystal a axis are observed. In contrast, the delocalized electronic states detectable by quasiparticle interference imaging are dispersive along the b axis only and are consistent with a nematic alpha(2) band with an apparent band folding having wave vector (q) over right arrow congruent to +/- 2 pi/8a(Fe-Fe) along the a axis. All these effects rotate through 90 degrees at orthorhombic twin boundaries, indicating that they are bulk properties. As none of these phenomena are expected merely due to crystal symmetry, underdoped ferropnictides may exhibit a more complex electronic nematic state than originally expected.

URL<Go to ISI>://000273394000028
DOIDoi 10.1126/Science.1181083