2023/04/10 by Seo, Dongmin, Ahn, Gihyeon, Rimal, Gaurab +6
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Other Condensed Matter (cond-mat.other)
paper · doi:10.48550/arxiv.2304.04432
We performed polarized reflection and transmission measurements on the layered conducting oxide \rm PdCoO2 thin films. For the ab-plane, an optical peak near Ω ≈ 750 cm-1 drives the scattering rate γ*(ω) and effective mass m*(ω) of the Drude carrier to increase and decrease respectively for ω \geqq Ω. For the c-axis, a longitudinal optical phonon (LO) is present at Ω as evidenced by a peak in the loss function Im[-1/εc(ω)]. Further polarized measurements in different light propagation (q) and electric field (E) configurations indicate that the Peak at Ω results from an electron-phonon coupling of the ab-plane carrier with the c-LO phonon, which leads to the frequency-dependent γ*(ω) and m*(ω). This unusual interaction was previously reported in high-temperature superconductors (HTSC) between a non-Drude, mid-infrared band and a c-LO. On the contrary, it is the Drude carrier that couples in \rm PdCoO2. The coupling between the ab-plane Drude carrier and c-LO suggests that the c-LO phonon may play a significant role in the characteristic ab-plane electronic properties of \rm PdCoO2 including the ultra-high dc-conductivity, phonon-drag, and hydrodynamic electron transport.