4 research outputs found
Interaction of in-plane Drude carrier with c -axis phonon in PdCoO2
Funding: E.C. was supported by the NRF-2021R1A2C1009073 of Korea funded by the Ministry of Education. D.S. was partially supported by MOLIT as an Innovative Talent Education Program for Smart City. The work at Rutgers University is supported by the National Science Foundation’s DMR2004125 and the Army Research Office’s W911NF2010108. S.B.C. was supported by the National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIT)(NRF-2023R1A2C1006144, NRF-2020R1A2C1007554, and NRF-2018R1A6A1A06024977). Research in Dresden benefits from the environment provided by the DFG Cluster of Excellence ct.qmat (EXC 2147, project ID 390858490). The work at HYU was supported by the NRF grant funded by the Korean government (MSIT) (2022R1F1A1072865), the BrainLink program funded by MSIT (2022H1D3A3A01077468), and the Quantum Simulator Development Project for Materials Innovation through the NRF funded by MSIT (2023M3K5A1094813).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)]. 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 1/τ(ω) and m*(ω). This unusual interaction was previously reported in high-temperature superconductors (HTSC) between a non-Drude, mid-infrared (IR) band and a c-LO. On the contrary, it is the Drude carrier that couples in 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 PdCoO2, including the ultra-high dc-conductivity, phonon-drag, and hydrodynamic electron transport.Publisher PDFPeer reviewe
Interaction of in-plane Drude carrier with c-axis phonon in
We performed polarized reflection and transmission measurements on the
layered conducting oxide thin films. For the ab-plane, an optical
peak near 750 cm drives the scattering rate
and effective mass of the Drude carrier to
increase and decrease respectively for . For the
c-axis, a longitudinal optical phonon (LO) is present at as evidenced
by a peak in the loss function Im[]. Further
polarized measurements in different light propagation (q) and electric field
(E) configurations indicate that the Peak at results from an
electron-phonon coupling of the ab-plane carrier with the c-LO phonon, which
leads to the frequency-dependent and . 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 . 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 including the ultra-high dc-conductivity, phonon-drag, and
hydrodynamic electron transport.Comment: 4 figure
Optical transitions of a single nodal ring in SrAs: radially and axially resolved characterization
We perform polarized optical reflection measurements on a single nodal-ring
semimetal . For the radial and axial directions of the ring, the
optical conductivity exhibits a flat absorption
over a certain frequency range. In addition, a
prominent optical peak appears at 2 = 30 meV. For
comparison, we theoretically calculate using an effective
model Hamiltonian and first-principles calculations, which successfully
reproduces the data for both directions. The
establishes that the universal power-law of optical conductivity holds robustly
in the nodal ring. Furthermore, key quantities of the nodal ring such as the
band overlap energy, average ring radius, ring ellipticity, and the SOC-gap are
determined from this comparative study. As temperature increases,
shows a substantial change, suggesting that a -driven
evolution occurs in the nodal ring.Comment: 6 pages, 4 figures + supplemental material (18 pages, 7 figures
Wafer-Scale and Wrinkle-Free Epitaxial Growth of Single-Orientated Multilayer Hexagonal Boron Nitride on Sapphire
Large-scale growth of high-quality hexagonal boron nitride has been a challenge in two-dimensional-material-based electronics. Herein, we present wafer-scale and wrinkle-free epitaxial growth of multilayer hexagonal boron nitride on a sapphire substrate by using high-temperature and low-pressure chemical vapor deposition. Microscopic and spectroscopic investigations and theoretical calculations reveal that synthesized hexagonal boron nitride has a single rotational orientation with AA' stacking order. A facile method for transferring hexagonal boron nitride onto other target substrates was developed, which provides the opportunity for using hexagonal boron nitride as a substrate in practical electronic circuits. A graphene field effect transistor fabricated on our hexagonal boron nitride sheets shows clear quantum oscillation and highly improved carrier mobility because the ultraflatness of the hexagonal boron nitride surface can reduce the substrate-induced degradation of the carrier mobility of two-dimensional materialsclos