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

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 most direct probe of the effects of an optical excitation on the band structure of a material. In particular, tr-ARPES in the extreme ultraviolet (VUV) range gives access to the ultrafast dynamics over the entire Brillouin zone. VUV tr-ARPES experiments can now be performed at the ASTRA (ARPES Spectrometer for Time-Resolved Applications) end station of Harmonium, at LACUS. Its capabilities are illustrated by measurements of the ultrafast electronic response of ZrSiTe, a novel topological semimetal characterized by linearly dispersing states located at the Brillouin zone boundary.

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Christopher Alexander Arrell, Helmuth Berger, Philippe Bugnon, Majed Chergui, Alberto Crepaldi, Gianmarco Gatti, Marco Grioni, Arnaud Magrez, José Javier Pancracio Ojeda Andara, Silvan Dino Marcos Roth, Frank van Mourik
Schweizerische Chemische Gesellschaft, 2017
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Time-resolved ARPES at LACUS: Band Structure and Ultrafast Electron Dynamics of Solids

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 most direct probe of the effects of an optical excitation on the band structure of a material. In particular, tr-ARPES in the extreme ultraviolet (VUV) range gives access to the ultrafast dynamics over the entire Brillouin zone. VUV tr-ARPES experiments can now be performed at the ASTRA (ARPES Spectrometer for Time-Resolved Applications) end station of Harmonium, at LACUS. Its capabilities are illustrated by measurements of the ultrafast electronic response of ZrSiTe, a novel topological semimetal characterized by linearly dispersing states located at the Brillouin zone boundary.

2017

Direct photoemission spectroscopy and electronic properties of in situ grown, strained high-T-c and related oxide films

Mike Abrecht, Dominique Cloëtta, Giorgio Margaritondo, Davor Pavuna, Dusan Vobornik

We have optimized laser ablation thin film deposition and transfer procedures within synchrotron vault, specifically to perform angle-integrated and angle-resolved photoemission spectroscopy (ARPES) on high-T-c and related films without cleaving the samples. However, the chain-containing phases like YBCO-123 easily loose surface oxygen and do not exhibit stable Fermi edge, hence are not suitable for ARPES studies. Direct in situ ARPES studies on strained LSCO-214 films show striking strain effects on the electronic structure. The Fermi surface (FS) of LSCO evolves with doping, yet changes even more significantly with strain. The strain changes the FS topology from hole-like to electron-like, and causes band dispersion along k(x) and the Fermi level crossing before the Brillouin zone boundary, in sharp contrast to the 'usual' flat band remaining approximate to 30 meV below E-F measured on unstrained samples. The associated reduction of the density of states does not diminish the superconductivity; T-c is enhanced in all our strained samples. Implications for the evolving high-T-c theory and studies of nano-engineered film heterostructures are briefly discussed. (C) 2004 Elsevier Ltd. All rights reserved.

2004

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

Helmuth Berger, Alberto Crepaldi, Marco Grioni, 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 compounds increases with the number of layers, motivating the interest in multilayered heterostructures or bulk materials. By means of angle-resolved photoemission spectroscopy (ARPES) measurements and density functional theory calculations, we compare the electronic band structure of bulk epsilon-GaSe and epsilon-InSe semiconductors. We focus our attention on the top valence band of the two compounds along main symmetry directions, discussing the effect of spin-orbit coupling and contributions from post-transition-metal (Ga or In) and Se atoms. Our results show that the top valence band at Gamma point is dominated by Se p(z) states, while the main effect of Ga or In appears more deeply in binding energy, at the Brillouin zone corners, and in the conduction band. These findings explain also the experimental observation of a hole effective mass rather insensitive to the post-transition metal. Finally, by means of spin-resolved ARPES and surface band structure calculations we describe Rashba-Bychkov spin splitting of surface states in epsilon-InSe.

AMER PHYSICAL SOC2020

Photoemission spectroscopy

Photoemission spectroscopy (PES), also known as photoelectron spectroscopy, refers to energy measurement of electrons emitted from solids, gases or liquids by the photoelectric effect, in order to d

Electronic band structure

In solid-state physics, the electronic band structure (or simply band structure) of a solid describes the range of energy levels that electrons may have within it, as well as the ranges of energy th

Electronic structure

In physics, electronic structure is the state of motion of electrons in an electrostatic field created by stationary nuclei. The term encompasses both the wave functions of the electrons and the ene