Complex hybridization physics in CaFe2As2 - a high resolution hard x-ray photoemission study. (15th May 2020)

• Record Type: Journal Article
• Authors: Pandeya, Ram Prakash; Pramanik, Arindam; Sakhya, Anup Pradhan; Thamizhavel, A; Maiti, Kalobaran
• Is Part Of: Journal of physics. Volume 32:Number 33(2020)
• Publication Date: 2020-05-15
• Subjects: surface bulk differences -- hard x-ray photoemission -- hybridization physics -- plasmon excitation -- Fe based superconductors; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/ab86f0
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Employing high resolution hard x-ray photoemission spectroscopy, we investigate the electronic structure of an exotic Fe-based superconductor, CaFe2 As2, which exhibits rich temperature pressure phase diagram and dichotomy on achieving superconductivity on application of pressure. The experimental valence band spectra exhibit significant differences for experiments at different surface sensitivities. We discover that the change in angle between light polarization and surface normal leads to similar orbital selective spectral response suggesting requirement of different methodology to probe the surface-bulk differences. Thus, the final state effects of the core level spectroscopy has been exploited to reveal the depth-resolved information. Strong features related to plasmon excitations have been observed in various core level spectra. Ca 2p spectra exhibit evidence of significant hybridization with the conduction electrons, and distinct features corresponding to the surface and bulk electronic structures while As core levels remain unaffected. The depth-resolved Fe 2p spectra at different temperatures exhibit interesting features suggesting structural anomaly may be a bulk property. All these results reveal complexity in the hybridization physics between Fe, As and Ca states presumably leading to exoticity in this material.