Publications by Alberto Crepaldi

Diversity of radial spin textures in chiral materials

Oleg Yazyev, Daniel Gosalbez Martinez, Alberto Crepaldi

We introduce a classification of the radial spin textures in momentum space that emerge at the high-symmetry points in crystals characterized by nonpolar chiral point groups (D2, D3, D4, D6, T, O). Based on the symmetry constraints imposed by these point g ...

Amer Physical Soc2023

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

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

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

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

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

Photoinduced long-lived state in FeSe0.4Te0.6

Alberto Crepaldi

Fe(Sex)Te(1-)x compounds display a rich phase diagram, ranging from the nematicity of FeSe to the (pi, pi) magnetism of FeTe. We focus on FeSe0.4Te0.6, and exploit tr-ARPES to study its ultrafast electron dynamics following photoexcitation by near-infrared ...

ELSEVIER2021

Origin of large magnetoresistance in the topological nonsymmorphic semimetal TaSe3

Jean-Philippe Ansermet, Oleg Yazyev, Quansheng Wu, Shengnan Zhang, Daniel Gosalbez Martinez, Michele Puppin, Helmuth Berger, Alberto Crepaldi, Gabriel Albert Autes, Gianmarco Gatti

TaSe3 is a layered van der Waals semimetal with several inverted band gaps throughout the entire Brillouin zone and nontrivial Z(2) topological indices, which place it at the boundary between a strong and a weak topological phase. Our transport experiments ...

2021

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

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

Majed Chergui, Henrik Moodysson Rønnow, Marco Grioni, Oleg Yazyev, Luc Testa, Daniel Gosalbez Martinez, Michele Puppin, Philippe Bugnon, Luca Moreschini, Alberto Crepaldi

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

Marco Grioni, Helmuth Berger, Alberto Crepaldi, Daniela Pacilè

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

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

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

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

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