Rocksalt CeO epitaxial thin film as a heavy-fermion system transiting from p-type metal to partially compensated n-type metal by 4f delocalization

Rocksalt CeO (001) epitaxial thin films were synthesized and their electronic properties were investigated. A simple 4 f15d1electronic configuration with 4 f -5d hybridization in CeO was confirmed by x-ray photoemission and absorption spectroscopy. While 5d conduction holes governed the metallic conduction at high temperatures, a partially compensated n-type conduction appeared below similar to 10 K with a rapid decrease in resistivity correspond-ing to a Fermi liquid state. The hole mobility was as high as 646 cm2 V-1 s-1 at 2 K in contrast to the two decades lower electron mobility, reflecting the large and small dispersion of 5d and 4 f bands, respectively. At 0.8 K, a resistivity minimum was observed as a manifestation of the Kondo effect, indicating partial 4 f localization. These results represented that the significant 4 f-5d hybridization induced a Kondo coherent state in CeO with a short Ce-Ce interionic distance unlike the other antiferromagnetic Ce chalcogenides.