Cyclotron resonance (CR) measurements for the Fe-based superconductor KFe2As2 are performed. One signal for CR is observed, and is attributed to the two-dimensional α Fermi surface at the Γ point. We found a large discrepancy in the effective masses of CR [(3.4±0.05)me (me is the free electron mass)] and de-Haas van Alphen (dHvA) results, a direct evidence of mass enhancement due to electronic correlation. A comparison of the CR and dHvA results shows that both intra- and interband electronic correlations contribute to the mass enhancement in KFe2As2.
@article{arxiv.1111.1884,
title = {Cyclotron resonance and mass enhancement by electron correlation in KFe$_2$As$_2$},
author = {Motoi Kimata and Taichi Terashima and Nobuyuki Kurita and Hidetaka Satsukawa and Atsushi Harada and Kouta Kodama and Kanji Takehana and Yasutaka Imanaka and Tadashi Takamasu and Kunihiro Kihou and Chul-Ho Lee and Hijiri Kito and Hiroshi Eisaki and Akira Iyo and Hideto Fukazawa and Yoh Kohori and Hisatomo Harima and Shinya Uji},
journal= {arXiv preprint arXiv:1111.1884},
year = {2015}
}