Publications related to Ultrafast Dynamics of Charge Density Waves in 4H(b)-TaSe2 Probed by Femtosecond Electron Diffraction

Ultrafast Electron Microscopy of Nanoscale Charge Dynamics in Semiconductors

Fabrizio Carbone, Ivan Madan, Giovanni Maria Vanacore, Francesco Barantani, Ido Kaminer, Kangpeng Wang, Simone Gargiulo

The ultrafast dynamics of charge carriers in solids plays a pivotal role in emerging optoelectronics, photonics, energy harvesting, and quantum technology applications. However, the investigation and direct visualization of such nonequilibrium phenomena re ...

AMER CHEMICAL SOC2023

Impact of quantum-chemical metrics on the machine learning prediction of electron density

Anne-Clémence Corminboeuf, Alberto Fabrizio, Ksenia Briling

Machine learning (ML) algorithms have undergone an explosive development impacting every aspect of computational chemistry. To obtain reliable predictions, one needs to maintain a proper balance between the black-box nature of ML frameworks and the physics ...

AMER INST PHYSICS2021

Catalyzing Bond-Dissociation in Graphene via Alkali-Iodide Molecules

Klaus Kern, Stephan Rauschenbach, Sabine Abb, Sven Alexander Szilagyi, Hannah Julia Ochner

Atomic design of a 2D-material such as graphene can be substantially influenced by etching, deliberately induced in a transmission electron microscope. It is achieved primarily by overcoming the threshold energy for defect formation by controlling the kine ...

WILEY-V C H VERLAG GMBH2021

Bulk and Surface Electronic Structure of the Dual-Topology Semimetal Pt2HgSe3

Nicola Marzari, Marco Gibertini, Antimo Marrazzo

We report high-resolution angle-resolved photoemission measurements on single crystals of Pt2HgSe3 grown by high-pressure synthesis. Our data reveal a gapped Dirac nodal line whose (001) projection separates the surface Brillouin zone in topological and tr ...

AMER PHYSICAL SOC2020

Statics and dynamics of multivalley charge density waves in Sb (111)

Daniele Dragoni, Davide Campi

Charge density waves (CDWs), periodic modulations of the charge density, are among the most abundant and non-trivial ordered phases in condensed matter. Here we demonstrate the occurrence of multi-valley charge density waves (MV-CDW) on the semimetal Sb(11 ...

Springer2019

Imaging electron-density fluctuations by multidimensional X-ray photon-coincidence diffraction

Jérémy Raymond Jean Maurice Rouxel

The ultrafast spontaneous electron-density fluctuation dynamics in molecules is studied theoretically by off-resonant multiple X-ray diffraction events. The time- and wavevector-resolved photon-coincidence signals give an image of electron-density fluctuat ...

National Academy of Sciences2019

Revealing the role of electrons and phonons in the ultrafast recovery of charge density wave correlations in 1T-TiSe2

Helmuth Berger, Arnaud Magrez, Matthias Wolf

Using time-and angle-resolved photoemission spectroscopy with selective near-and midinfrared photon excitations, we investigate the femtosecond dynamics of the charge density wave ( CDW) phase in 1T-TiSe2 as well as the dynamics of CDW fluctuations at 240 ...

Amer Physical Soc2016

Orbital textures and charge density waves in transition metal dichalcogenides

Helmuth Berger

Low-dimensional electron systems, as realized in layered materials, often tend to spontaneously break the symmetry of the underlying nuclear lattice by forming so-called density waves(1); a state of matter that at present attracts enormous attention(2-6). ...

Nature Publishing Group2015

Strongly enhanced charge-density-wave order in monolayer NbSe2

Helmuth Berger, László Forró

Two-dimensional materials possess very different properties from their bulk counterparts. While changes in single-particle electronic properties have been investigated extensively(1-3), modifications in the many-body collective phenomena in the exact two-d ...

Nature Publishing Group2015

Microscopic evidence for strong periodic lattice distortion in two-dimensional charge-density wave systems

Helmuth Berger, Ji Dai

In quasi-two-dimensional electron systems of layered transition metal dichalcogenides (TMDs) there is still controversy about the nature of the transitions to charge-density wave (CDW) phases, i.e., whether they are described by a Peierls-type mechanism or ...

Amer Physical Soc2014

Sample preparation methods for femtosecond electron diffraction experiments

Helmuth Berger

Exploring the dynamics of Charge density wave system 1T-TaS2 via femtosecond electron diffraction demonstrated the power of this technique for studying ultrafast structural phenomena in strongly correlated electron materials [1]. The results revealed first ...

Elsevier Science Bv2013

Ultrafast inter-ionic charge transfer of transition-metal complexes mapped by femtosecond X-ray powder diffraction

Majed Chergui

The transient electronic and molecular structure arising from photoinduced charge transfer in transition metal complexes is studied by X-ray powder diffraction with a 100 fs temporal and atomic spatial resolution. Crystals containing a dense array of Fe(II ...

American Institute of Physics2013

Imaging of high-Q cavity optical modes by electron energy-loss microscopy

Romuald Houdré, Marco Cantoni, Nicolas Le Thomas, Cécile Hébert, Duncan Thomas Lindsay Alexander

We show a technique that images the intensity distribution and local state of polarization of the optical field of high-quality factor optical modes confined in dielectric planar photonic crystal nanocavities. Based on energy-loss spectroscopy of swift ele ...

Amer Physical Soc2013

Evidence for a Peierls phase-transition in a three-dimensional multiple charge-density waves solid

Majed Chergui, Mathieu Julien Gino Cottet, Fabrizio Carbone, Thomas James Penfold

The effect of dimensionality on materials properties has become strikingly evident with the recent discovery of graphene. Charge ordering phenomena can be induced in one dimension by periodic distortions of a material's crystal structure, termed Peierls or ...

National Academy of Sciences2012

Nonthermal Melting of a Charge Density Wave in TiSe2

Paul Beaud

We use time-resolved optical reflectivity and x-ray diffraction with femtosecond resolution to study the dynamics of the structural order parameter of the charge density wave phase in TiSe2. We find that the energy density required to melt the charge densi ...

American Physical Society2011

Snapshots of cooperative atomic motions in the optical suppression of charge density waves

Helmuth Berger

Macroscopic quantum phenomena such as high-temperature superconductivity, colossal magnetoresistance, ferrimagnetism and ferromagnetism arise from a delicate balance of different interactions among electrons, phonons and spins on the nanoscale(1). The stud ...

2010