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Surface of quantum materials often exhibits significantly different behaviorthan the bulk due to changed topologies and symmetry protections. Theoutstanding problem is to find out if the exoticity of a material is linked tothe changed topology at the surface or it is a bulk property. Hard x-rayphotoemission spectroscopy (HAXPES) is a significantly bulk sensitive technique(escape depth of valence electrons is about 40 \AA\ for 6 keV photon energy)and the probing depth can be tuned by changing the electron emission angle.Therefore, HAXPES is often used to reveal the surface-bulk differences in amaterial. Here, we show that the delineation of surface-bulk differences in thevalence band spectral functions using this method is highly non-trivial due tothe complexity arising from linear dichroic effect in addition to the change insurface sensitivity. We show that core level spectra can be used to reveal thesurface-bulk differences in the electronic structure. The Ca 2p spectra exhibitevidence of significant hybridization with the conduction electrons revealingtheir importance in the electronic properties of the system as also found forthe charge reservoir layers in cuprate superconductors. The Fe 2p core levelspectra as a function of bulk sensitivity and temperature reveals an unusualscenario; while the surface electronic structure corroborates well with theobserved phase transitions of the system, the bulk spectra exhibit signature ofadditional structural phases providing a rare evidence of structural anomaly tobe a bulk property.

Complex hybridization physics and evidence of structural anomaly to be a bulk property in an exotic Fe-based compound, CaFe2As2