The localized-to-itinerant transition of f electrons lies at the heart of heavy-fermion physics, but has only been directly observed in single-layer Ce-based materials. Here, we report a comprehensive study on the electronic structure and nature of the Ce 4f electrons in the heavy-fermion superconductor Ce2PdIn8, a typical n=2 CenMmIn3n+2m compound, using high-resolution and 4d-4f resonant photoemission spectroscopies. The electronic structure of this material has been studied over a wide temperature range, and hybridization between f and conduction electrons can be clearly observed to form a Kondo resonance near the Fermi level at low temperatures. The characteristic temperature of the localized-to-itinerant transition is around 120 K, which is much higher than its coherence temperature Tcoh∼30K.
Bibliographical noteFunding Information:
We thank Diamond Light Source for the beam time at beamline I05 (Proposal No. SI16345) that contributed to the results presented here. We grateful acknowledge helpful discussions with Dr. D. C. Peets. The work was supported by the National Science Foundation of China (Grants No. 11874330, No. 11274332, No. 11574337, No. 11704073, No. 11504342, and No. U1332209), and the National Key R&D Program of the MOST of China (Grants No. 2016YFA0300200 and No. 2017YFA0303104). Also, this work is supported by the National Science Centre (Poland) under Research Grants No. 2015/19/B/ST3/03158 and No. U1332209, and the Science Challenge Project No. TZ2016004. P.S.'s work at Ames Laboratory (electronic structure calculations) was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering. Ames Laboratory is operated for the US Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358. D.W.S is also supported by “Award for Outstanding Member in Youth Innovation Promotion Association CAS.”
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