Suk Bum Chung

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Abstract The concept of ferroelectricity is now often extended to include continuous inversion symmetry-breaking transitions in various metals and doped semiconductors. Paraelectric metals near ferroelectric quantum criticality, which we term ‘quantum paraelectric metals,’ possess soft transverse optical phonons which can have Rashba-type coupling to itinerant electrons in the presence of spin-orbit coupling.

Abstract We performed polarized reflection and transmission measurements on the layered conducting oxide PdCoO2 thin films. For the ab-plane, an optical peak near Ω ≈ 750 cm−1 drives the scattering rate 1/τ(ω) and effective mass m*(ω) of the Drude carrier to increase and decrease respectively for ω ≧ 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)].