Cyclotron Resonance and Mass Enhancement by Electron Correlation inKFe2As2
Physical Review Letters
Cyclotron resonance (CR) measurements for the Fe-based superconductor KFe_2As_2 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)m_e (m_e 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
... c correlations contribute to the mass enhancement in KFe_2As_2.