Sign inversion in the superconducting order parameter of LiFeAs inferred from Bogoliubov quasiparticle interference

Shun Chi; S. Johnston; G. Levy; S. Grothe; R. Szedlak; B. Ludbrook; Ruixing Liang; P. Dosanjh; S. A. Burke; A. Damascelli; D. A. Bonn; W. N. Hardy; Y. Pennec

doi:10.1103/physrevb.89.104522

arXiv · 1308.4413

Sign inversion in the superconducting order parameter of LiFeAs inferred from Bogoliubov quasiparticle interference

Shun Chi·S. Johnston·G. Levy·S. Grothe·R. Szedlak·B. Ludbrook·Ruixing Liang·P. Dosanjh·S. A. Burke·A. Damascelli·D. A. Bonn·W. N. Hardy·Y. Pennec

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Abstract

Quasiparticle interference (QPI) by means of scanning tunneling microscopy/spectroscopy (STM/STS), angle resolved photoemission spectroscopy (ARPES), and multi-orbital tight bind- ing calculations are used to investigate the band structure and superconducting order parameter of LiFeAs. Using this combination we identify intra- and interband scattering vectors between the hole (h) and electron (e) bands in the QPI maps. Discrepancies in the band dispersions inferred from previous ARPES and STM/STS are reconciled by recognizing a difference in the $k_z$ sensitivity for the two probes. The observation of both h-h and e-h scattering is exploited using phase-sensitive scattering selection rules for Bogoliubov quasiparticles. From this we infer an s$_\pm$ gap structure, where a sign change occurs in the superconducting order parameter between the e and h bands.

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Shun Chi, S. Johnston, G. Levy, S. Grothe, R. Szedlak, B. Ludbrook, Ruixing Liang, P. Dosanjh, S. A. Burke, A. Damascelli, D. A. Bonn, W. N. Hardy, Y. Pennec. 2013-08-20. Sign inversion in the superconducting order parameter of LiFeAs inferred from Bogoliubov quasiparticle interference. https://doi.org/10.1103/physrevb.89.104522

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