Electrical Control over Phonon Polarization in Strained Graphene

in Nano Letters (2021), 21(7), 2898--2904

Impact of many-body effects on Landau levels in graphene

in Physical Review Letters (2018), 120(18), 187701

We present magneto-Raman spectroscopy measurements on suspended graphene to investigate the charge carrier density-dependent electron-electron interaction in the presence of Landau levels. Utilizing gate ... [more ▼]

We present magneto-Raman spectroscopy measurements on suspended graphene to investigate the charge carrier density-dependent electron-electron interaction in the presence of Landau levels. Utilizing gate-tunable magnetophonon resonances, we extract the charge carrier density dependence of the Landau level transition energies and the associated effective Fermi velocity vF. In contrast to the logarithmic divergence of vF at zero magnetic field, we find a piecewise linear scaling of vF as a function of the charge carrier density, due to a magnetic-field-induced suppression of the long-range Coulomb interaction. We quantitatively confirm our experimental findings by performing tight-binding calculations on the level of the Hartree-Fock approximation, which also allow us to estimate an excitonic binding energy of ≈6  meV contained in the experimentally extracted Landau level transitions energies. [less ▲]

Line shape of the Raman 2D peak of graphene in van der Waals heterostructures

in Physica Status Solidi B. Basic Research (2016), 253(12), 2326--2330

Correspondence: On the nature of strong piezoelectricity in graphene on SiO2

in Nature Communications (2016), 7

Probing electronic lifetimes and phonon anharmonicities in high-quality chemical vapor deposited graphene by magneto-Raman spectroscopy

in Applied Physics Letters (2015), 107(23), 233105

Low B field magneto-phonon resonances in single-layer and bilayer graphene

in Nano Letters (2015), 15(3), 1547--1552

Raman spectroscopy on mechanically exfoliated pristine graphene ribbons

in Physica Status Solidi B. Basic Research (2014), 251(12), 2551--2555

Relaxation times and electron-phonon interaction in graphene quantum dots

Poster (2013, May 23)

Diffractive paths for weak localization in quantum billiards

in Physical Review. B (2008), 77(16),

We study the weak-localization effect in quantum transport through a clean ballistic cavity with regular classical dynamics. We address the question which paths account for the suppression of conductance ... [more ▼]

We study the weak-localization effect in quantum transport through a clean ballistic cavity with regular classical dynamics. We address the question which paths account for the suppression of conductance through a system where disorder and chaos are absent. By exploiting both quantum and semiclassical methods, we unambiguously identify paths that are diffractively backscattered into the cavity (when approaching the lead mouths from the cavity interior) to play a key role. Diffractive scattering couples transmitted and reflected paths and is thus essential to reproduce the weak-localization peak in reflection and the corresponding antipeak in transmission. A comparison of semiclassical calculations featuring these diffractive paths yields good agreement with full quantum calculations and experimental data. Our theory provides system-specific predictions for the quantum regime of few open lead modes and can be expected to be relevant also for mixed as well as chaotic systems. [less ▲]