Liu, Z.K.Yi, M.Zhang, Y.Hu, J.Yu, R.Zhu, J.-X.He, R.-H.Chen, Y.L.Hashimoto, M.Moore, R.G.Mo, S.-K.Hussain, Z.Si, Q.Mao, Z.Q.Lu, D.H.Shen, Z.-X.2016-06-102016-06-102015Liu, Z.K., Yi, M., Zhang, Y., et al.. "Experimental observation of incoherent-coherent crossover and orbital-dependent band renormalization in iron chalcogenide superconductors." <i>Physical Review B,</i> 92, no. 23 (2015) American Physical Society: 235138. http://dx.doi.org/10.1103/PhysRevB.92.235138.https://hdl.handle.net/1911/90495The level of electronic correlation has been one of the key questions in understanding the nature of superconductivity. Among the iron-based superconductors, the iron chalcogenide family exhibits the strongest electron correlations. To gauge the correlation strength, we performed a systematic angle-resolved photoemission spectroscopy study on the iron chalcogenide series Fe1+ySexTe1−x (0<x<0.59), a model system with the simplest structure. Our measurement reveals an incoherent-to-coherent crossover in the electronic structure as the selenium ratio increases and the system evolves from a weakly localized to a more itinerant state. Furthermore, we found that the effective mass of bands dominated by the dxy orbital character significantly decreases with increasing selenium ratio, as compared to the dxz/dyz orbital-dominated bands. The orbital-dependent change in the correlation level agrees with theoretical calculations on the band structure renormalization, and may help to understand the onset of superconductivity in Fe1+ySexTe1−x.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Experimental observation of incoherent-coherent crossover and orbital-dependent band renormalization in iron chalcogenide superconductorsJournal articlehttp://dx.doi.org/10.1103/PhysRevB.92.235138