Publications by Marco Grioni | EPFL Graph Search

Light-induced renormalization of the band structure of chiral tellurium

Marco Grioni, Majed Chergui, Serhii Polishchuk, Michele Puppin, Ji Dai

Chirality in tellurium arises from a Peierls distortion driven by strong electron-phonon coupling, making this material a unique candidate for observing a light-induced topological phase transition. Using time- and angle-resolved photoelectron spectroscopy ...

2024

High-resolution MHz time- and angle-resolved photoemission spectroscopy based on a tunable vacuum ultraviolet source

Marco Grioni, Thomas La Grange, Henrik Moodysson Rønnow, Fabrizio Carbone, Jan Hugo Dil, Michele Puppin, Fei Guo

The time- and angle-resolved photoemission spectroscopy (trARPES) allows for direct mapping of the electronic band structure and its dynamic response on femtosecond timescales. Here, we present a new ARPES system, powered by a new fiber-based femtosecond l ...

Aip Publishing2024

Nanoscale-Resolved Surface-to-Bulk Electron Transport in CsPbBr3 Perovskite

Marco Grioni, Majed Chergui, Alberto Crepaldi, Nicola Marzari, Nicola Colonna, Gianmarco Gatti, Serhii Polishchuk, Michele Puppin

Describing the nanoscale charge carrier transport at surfaces and interfaces is fundamental for designing highperformance optoelectronic devices. To achieve this, we employ time-and angle-resolved photoelectron spectroscopy with ultraviolet pump and extrem ...

AMER CHEMICAL SOC2022

Optically induced changes in the band structure of the Weyl charge-density-wave compound (TaSe4)(2)I

Helmuth Berger, Marco Grioni, Majed Chergui, Oleg Yazyev, Alberto Crepaldi, Daniel Gosalbez Martinez, Michele Puppin

Collective modes are responsible for the emergence of novel quantum phases in topological materials. In the quasi-one dimensional (1D) Weyl semimetal (TaSe4)(2)I < i , a charge density wave (CDW) opens band gaps at the Weyl points, thus turning the system ...

2022

Hidden bulk and surface effects in the spin polarization of the nodal-line semimetal ZrSiTe

Helmuth Berger, Marco Grioni, Arnaud Magrez, Oleg Yazyev, Alberto Crepaldi, Mauro Fanciulli, Gianmarco Gatti, Daniel Gosalbez Martinez, Silvan Dino Marcos Roth

Local inversion symmetry breaking in centrosymmetric materials can lead to large spin polarization of the electronic band structure in separate sectors of the unit cell. Here, the authors reveal such hidden spin polarisation in ZrSiTe using spin and angle ...

NATURE RESEARCH2021

Radial Spin Texture of the Weyl Fermions in Chiral Tellurium

Philippe Bugnon, Marco Grioni, Majed Chergui, Oleg Yazyev, Luca Moreschini, Henrik Moodysson Rønnow, Alberto Crepaldi, Simon Karl Moser, Luc Testa, Mauro Fanciulli, Edoardo Martino, Gianmarco Gatti, Daniel Gosalbez Martinez, Silvan Dino Marcos Roth, Serhii Polishchuk, Michele Puppin

Trigonal tellurium, a small-gap semiconductor with pronounced magneto-electric and magneto-optical responses, is among the simplest realizations of a chiral crystal. We have studied by spin- and angle-resolved photoelectron spectroscopy its unconventional ...

AMER PHYSICAL SOC2020

Insight into the electronic structure of semiconducting epsilon-GaSe and epsilon-InSe

Helmuth Berger, Marco Grioni, Daniela Pacilè, Alberto Crepaldi

Metal monochalcogenides (MX) have recently been rediscovered as two-dimensional materials with electronic properties highly dependent on the number of layers. Although some intriguing properties appear in the few-layer regime, the carrier mobility of MX co ...

AMER PHYSICAL SOC2020

Evidence of Large Polarons in Photoemission Band Mapping of the Perovskite Semiconductor CsPbBr3

Marco Grioni, Majed Chergui, Alberto Crepaldi, Nicola Marzari, Nicola Colonna, Gianmarco Gatti, Serhii Polishchuk, Thomas Roland Barillot, Michele Puppin, Riccardo De Gennaro, Matthias Wolf

Lead-halide perovskite (LHP) semiconductors are emergent optoelectronic materials with outstanding transport properties which are not yet fully understood. We find signatures of large polaron formation in the electronic structure of the inorganic LHP CsPbB ...

AMER PHYSICAL SOC2020

Light-Induced Renormalization of the Dirac Quasiparticles in the Nodal-Line Semimetal ZrSiSe

Helmuth Berger, Philippe Bugnon, Marco Grioni, Majed Chergui, Arnaud Magrez, Luca Moreschini, Alberto Crepaldi, Simon Karl Moser, Gianmarco Gatti, Serhii Polishchuk, Michele Puppin

In nodal-line semimetals, linearly dispersing states form Dirac loops in the reciprocal space with a high degree of electron-hole symmetry and a reduced density of states near the Fermi level. The result is reduced electronic screening and enhanced correla ...

2020

Unveiling the electronic transformations in the semi-metallic correlated-electron transitional oxide Mo8O23

Marco Grioni, Gianmarco Gatti

Mo8O23 is a low-dimensional chemically robust transition metal oxide coming from a prospective family of functional materials, MoO3-x, ranging from a wide gap insulator (x = 0) to a metal (x = 1). The large number of stoichometric compounds with intermedia ...

Nature Research2019

Photocarrier-induced band-gap renormalization and ultrafast charge dynamics in black phosphorus

Marco Grioni, Majed Chergui, Steven Roth, Alberto Crepaldi, Gianmarco Gatti, Michele Puppin

With its tunable band-gap and its unique optical and electronic properties black phosphorus (BP) opens exciting opportunities for optoelectronic nanotechnology. The band-gap extends from the visible to the mid-infrared spectral range, as a function of samp ...

2019

Orbitally selective breakdown of Fermi liquid quasiparticles in Ca1.8Sr0.2RuO4

Marco Grioni, Johan Juul Chang, Gianmarco Gatti

We present a comprehensive angle-resolved photoemission spectroscopy study of Ca1.8Sr0.2RuO4. Four distinct bands are revealed and along the Ru-O bond direction their orbital characters are identified through a light polarization analysis and comparison to ...

AMER PHYSICAL SOC2019

Polarization dependence of angle-resolved photoemission with submicron spatial resolution reveals emerging one-dimensionality of electrons in NbSe3

Helmuth Berger, Marco Grioni, Emmanouil Frantzeskakis, Miguel Angel Valbuena

In materials with nearly commensurate band filling the electron liquid may spontaneously separate into components with distinct properties, yielding complex intra- and interunit cell ordering patterns and a reduced dimensionality. Polarization-dependent an ...

AMER PHYSICAL SOC2019

Volatile two-dimensional electron gas in ultrathin BaTiO3 films

Marco Grioni, Luca Moreschini, Simon Karl Moser, Sara Fatale

We investigate the metallic surface state in ultrathin films of BaTiO3 by angle-resolved photoemission spectroscopy. We find Fermi-surface contours derived from the Ti 3d t(2g) conduction band, similar as in SrTiO3 but with broader spectral features due to ...

AMER PHYSICAL SOC2018

Kondo lattice excitation observed using resonant inelastic x-ray scattering at the YbM5 edge

Marco Grioni, Marco Guarise, Thorsten Schmitt

We present a study of the resonant inelastic scattering response of YbInCu4 excited at the tender YbM5 x-ray edge. In the high-temperature, paramagnetic phase, we observe a multiplet structure which can be understood at an ionic level. Upon cooling through ...

AMER PHYSICAL SOC2018

Strongly bound excitons in anatase TiO2 single crystals and nanoparticles

Helmuth Berger, Marco Grioni, Majed Chergui, Arnaud Magrez, Gerald Auböck, Simon Karl Moser, Edoardo Baldini

Anatase TiO2 is among the most studied materials for light-energy conversion applications, but the nature of its fundamental charge excitations is still unknown. Yet it is crucial to establish whether light absorption creates uncorrelated electron-hole pai ...

Nature Publishing Group2017

Electronic and magnetic excitations in the half-stuffed Cu-O planes of Ba2Cu3O4Cl2 measured by resonant inelastic x-ray scattering

Marco Grioni, Bruce Normand, Henrik Moodysson Rønnow, Peter Babkevich, Sara Fatale, Noore Elahi Shaik, Claudia Giuseppina Fatuzzo, Thorsten Schmitt

We use resonant inelastic x-ray scattering (RIXS) at the Cu L3 edge to measure the charge and spin excitations in the “half-stuffed” Cu-O planes of the cuprate antiferromagnet Ba2Cu3O4Cl2. The RIXS line shape reveals distinct contributions to the dd excita ...

2017

Hallmarks of Hunds coupling in the Mott insulator Ca2RuO4

Marco Grioni, Henrik Moodysson Rønnow, Simon Karl Moser, Johan Juul Chang, Claudia Giuseppina Fatuzzo, Gianmarco Gatti

A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realized in Ca2RuO4. Progress in understanding the nature of this Mott insulating phase has been impeded by the lack of knowledge about the low-energy electronic str ...

Nature Research2017

Harmonium: An Ultrafast Vacuum Ultraviolet Facility

Marco Grioni, Marcel Drabbels, Majed Chergui, Frank van Mourik, Christopher Alexander Arrell, Alberto Crepaldi, José Javier Pancracio Ojeda Andara, Andrew Daniel Bonnar Clark, Gianmarco Gatti, Luca Longetti, Silvan Dino Marcos Roth

Harmonium is a vacuum ultraviolet (VUV) photon source built within the Lausanne Centre for Ultrafast Science (LACUS). Utilising high harmonic generation, photons from 20-110 eV are available to conduct steady-state or ultrafast photoelectron and photoion s ...

Swiss Chemical Soc2017

Persistence of a surface state arc in the topologically trivial phase of MoTe2

Helmuth Berger, Philippe Bugnon, Marco Grioni, Arnaud Magrez, Oleg Yazyev, Alberto Crepaldi, Gabriel Albert Autes

The prediction of Weyl fermions in the low-temperature noncentrosymmetric 1T' phase of MoTe2 still awaits clear experimental confirmation. Here, we report angle-resolved photoemission (ARPES) data and ab initio calculations that reveal a surface state arc ...

Amer Physical Soc2017