Publications de Philippe Bugnon

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

Light-induced charge transfer at the CH3NH3PbI3/TiO2 interface-a low-temperature photo-electron paramagnetic resonance assay

Philippe Bugnon, László Forró, Andrzej Sienkiewicz, Bálint Náfrádi, Endre Horvath, Péter Szirmai, Pavao Roko Andricevic, Anastasiia Glushkova, Márton Kollár, Konstantins Mantulnikovs

The performance of organic-inorganic metal halide perovskites-based (MHPs) photovoltaic devices critically depends on the design and material properties of the interface between the light-harvesting MHP layer and the electron transport layer (ETL). Therefo ...

2020

Crystallization and Organic Field-Effect Transistor Performance of a Hydrogen-Bonded Quaterthiophene

Philippe Bugnon, Rosario Scopelliti, Stéphane Suarez, Anne-Clémence Corminboeuf, Holger Frauenrath, Jan Gebers, Riccardo Petraglia, Piotr De Silva, Bilal Özen

Crystalline thin films of pi-conjugated molecules are relevant as the active layers in organic electronic devices. Therefore, materials with enhanced control over the supramolecular arrangement, crystallinity, and thin-film morphology are desirable. Herein ...

2020

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

Universal scattering response across the type-II Weyl semimetal phase diagram

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Stefan Peter Muff, Jan Hugo Dil, Mauro Fanciulli, Andrew Patton Weber

2018

Evidence of a Coulomb-Interaction-Induced Lifshitz Transition and Robust Hybrid Weyl Semimetal in Td−MoTe2

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Joël Mesot, Kazimierz Conder, Jan Hugo Dil

2018

Spin-Resolved Electronic Response to the Phase Transition in MoTe2

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Stefan Peter Muff, Jan Hugo Dil, Mauro Fanciulli, Andrew Patton Weber, Nan Xu

2018

Dirac nodal lines and flat-band surface state in the functional oxide RuO2

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Simon Karl Moser

The efficiency and stability of RuO2 in electrocatalysis has made this material a subject of intense fundamental and industrial interest. The surface functionality is rooted in its electronic and magnetic properties, determined by a complex interplay of la ...

AMER PHYSICAL SOC2018

Bulk diffusive relaxation mechanisms in optically excited topological insulators

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Alberto Crepaldi

The possibility to inject spin currents in topological insulators (TIs) by ultrashort optical pulses has stimulated intense studies of their out-of-equilibrium electronic properties. However, a comprehensive description of the electronic relaxation dynamic ...

Amer Physical 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

Electronic Phase Separation and Dramatic Inverse Band Renormalization in the Mixed-Valence Cuprate LiCu2O2

Helmuth Berger, Philippe Bugnon, Marco Grioni, Arnaud Magrez, Luca Moreschini, Simon Karl Moser, Gianmarco Gatti

We measured, by angle-resolved photoemission spectroscopy, the electronic structure of LiCu2O2, a mixed-valence cuprate where planes of Cu(I) (3d(10)) ions are sandwiched between layers containing one-dimensional edge-sharing Cu(II) (3d(9)) chains. We find ...

Amer Physical Soc2017

BiTeCl and BiTeBr: A comparative high-pressure optical study

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Oleg Yazyev, Ana Akrap, Gabriel Albert Autes

We here report a detailed high-pressure infrared transmission study of BiTeCl and BiTeBr. We follow the evolution of two band transitions: the optical excitation beta between two Rashba-split conduction bands, and the absorption. across the band gap. In th ...

Amer Physical Soc2017

Time-resolved ARPES at LACUS: Band Structure and Ultrafast Electron Dynamics of Solids

Helmuth Berger, Philippe Bugnon, Marco Grioni, Majed Chergui, Frank van Mourik, Arnaud Magrez, Christopher Alexander Arrell, Alberto Crepaldi, José Javier Pancracio Ojeda Andara, Gianmarco Gatti, Silvan Dino Marcos Roth

The manipulation of the electronic properties of solids by light is an exciting goal, which requires knowledge of the electronic structure with energy, momentum and temporal resolution. Time- and angle-resolved photoemission spectroscopy (tr-ARPES) is the ...

2017

Experimental determination of the bulk Rashba parameters in BiTeBr

Helmuth Berger, Philippe Bugnon, Arnaud Magrez

Shubnikov-de Haas (SdH) oscillations, Hall effect, and optical reflectance (R(omega)) measurements have been performed on single crystals of BiTeBr. Under magnetic fields up to 32 tesla and at temperatures as low as 0.4K, the SdH data shows a single oscill ...

IOP Publishing - EPL Association2016

Evidence for a Strong Topological Insulator Phase in ZrTe5

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Oleg Yazyev, Alberto Crepaldi, Luca Gragnaniello, Gabriel Albert Autes

The complex electronic properties of ZrTe5 have recently stimulated in-depth investigations that assigned this material to either a topological insulator or a 3D Dirac semimetal phase. Here we report a comprehensive experimental and theoretical study of bo ...

Amer Physical Soc2016

Advancing non-equilibrium ARPES experiments by a 9.3 eV coherent ultrafast photon source

Helmuth Berger, Philippe Bugnon, Alberto Crepaldi

The quest for investigating the non-equilibrium dynamics of the band structure of strongly-correlated materials over their entire Brillouin zone is a primary objective. However, the actual ultrafast UV light sources are not suitable for addressing several ...

Elsevier Science Bv2016

Momentum-Resolved Spin Dynamics of Bulk and Surface Excited States in the Topological Insulator Bi2Se3

Helmuth Berger, Philippe Bugnon, Marco Grioni, Alberto Crepaldi

The prospect of optically inducing and controlling a spin-polarized current in spintronic devices has generated wide interest in the out-of-equilibrium electronic and spin structure of topological insulators. In this Letter we show that only measuring the ...

Amer Physical Soc2015

Ultrafast Optical Control of the Electronic Properties of ZrTe5

Helmuth Berger, Philippe Bugnon, Marco Grioni, Arnaud Magrez, Alberto Crepaldi

We report on the temperature dependence of the ZrTe5 electronic properties, studied at equilibrium and out of equilibrium, by means of time and angle resolved photoelectron spectroscopy. Our results unveil the dependence of the electronic band structure ac ...

Amer Physical Soc2015

Engineering the topological surface states in the (Sb2)m−Sb2Te3(m=0–3) superlattice serie

Helmuth Berger, Philippe Bugnon, Marco Grioni, Arnaud Magrez, Oleg Yazyev, Alberto Crepaldi, Simon Karl Moser, Gabriel Albert Autes, Jens Christian Johannsen

We investigate the evolution of both the occupied and unoccupied electronic structure in representative compounds of the infinitely adaptive superlattice series (Sb2)m−Sb2Te3 (m=0–3) by means of angle-resolved photoemission spectroscopy and time-delayed tw ...

Amer Physical Soc2015

Electron-Phonon Coupling in the Bulk of Anatase TiO2 Measured by Resonant Inelastic X-Ray Spectroscopy

Helmuth Berger, Philippe Bugnon, Marco Grioni, Arnaud Magrez, Simon Karl Moser, Sara Fatale

We investigate the polaronic ground state of anatase TiO2 by bulk-sensitive resonant inelastic x-ray spectroscopy (RIXS) at the Ti L-3 edge. We find that the formation of the polaron cloud involves a single 95 meV phonon along the c axis, in addition to th ...

Amer Physical Soc2015