Defect modulated Raman response of KC8 single crystals

Abstract

AbstractIn situ experiments of graphite intercalation with potassium have been performed under high vacuum (HV) conditions. A detailed Raman lineshape analysis of the G‐line was applied to determine the intrinsic response of the stage one KC8 compound. Four defect‐modulated graphite single crystals were analyzed. We observe five vibrational modes (∼560, 1260, 1510, 1547, and 1563 cm−1). From a Breit–Wigner–Fano (BWF) lineshape analysis we elucidate the contribution of each vibrational mode observed. The intensity of the z‐axis mode (CZ) around ∼560 cm−1 varies depending on the defect modulated nominal KC8 crystal chosen. We prove that the intrinsic G‐line of KC8 is at 1510 cm−1, and it is strongly dependent on the actual defect content in the sample, which has important implications for the electron phonon coupling (EPC) responsible of superconductivity in this system.