Electronic Arts

(abrégé EA) est une société américaine fondée le et dont le siège se situe à Redwood City, dans le comté de San Mateo, en Californie. Electronic Arts est l'un des principaux développeurs et producteurs mondiaux de jeux vidéo. La société occupe la place de leader sur ce marché jusqu'en 2008, notamment grâce à des rachats de sociétés et de franchises de jeux, mais aussi en acquérant les droits de licences sportives, comme celles de la FIFA, la NBA, la NFL, ou encore celle de la LNH. Electronic Arts est, en 2013, la troisième plus grande société commercialisant des jeux vidéo, par chiffre d'affaires, après avoir été la en 2012 et 2011. Histoire Création Electronic Arts est fondé en 1982 par Trip Hawkins. Ce dernier découvre les ordinateurs en 1972 et a immédiatement l’idée de travailler dans la création de jeu vidéo. En 1975, il apprend l’ouverture de la première boutique d’ordinateurs des États-Unis et qu'Intel envisage de créer son premier micro-ordinateur. Il

The Interplay Between Structural and Electronic Degrees of Freedom in Superconductors

Mathieu Julien Gino Cottet

More than one hundred years after the discovery of superconductivity in Leiden, the intriguing physics of several unconventional classes of superconductors continue to fascinate and challenge scientists from all over the world. The majority of these compounds belongs to a major class of materials known as strongly correlated systems that exhibit interesting and diverse physical properties, like the high-temperature superconductivity, the Mott-insulator transition, the colossal magnetoresistance or the structurally-driven electronic phase transitions. Rigorous and deep investigations of the electronic properties, as well as their tunability, should lead to new attractive commercial applications. With the use of time-resolved experiments or bulk sensitive techniques, which represent the main subject of this thesis, the electronic and magnetic properties of strongly correlated type-II superconductors and high-temperature copper-oxide superconductors are accessible. These techniques take advantages of the photon tunability in the case of optical pump-probe by allowing one to record the transient response of the material over the whole visible spectrum, or in the case of X-ray diffraction, the tunability of the synchrotron radiation thanks to the slicing operating at the SLS (Swiss Light Source) in Villigen, Switzerland. Cryo-LTEM allows one to work across the (H ,T ) phase diagram of type-II superconductors, thus enabling the study of the coexistence between normal and superconducting state by careful regulation of the applied magnetic field near the specimen. The Chapter 1 (1) is a general introduction dedicated to the historical evolution of our understanding of superconductivity, according to the theories and general concepts used and developed is this thesis. Chapter 2 (3) is dedicated to the experimental techniques. A careful description of the different setups, as well as a theoretical development needed for the calculations is presented. In Chapter 3 (4), the investigation of magnesium diboride superconductor by means of cryo-LTEM is presented. By observing the field-dependent vortex lattices in this system and performing calculations using the theoretical frameworks developed by Ginzburg-Landau and Abrikosov, I found that this compound belongs to the type-II family [1], and not to the novel type 1.5 class of superconductor. In Chapter 4 (5), I present the investigation related the charge density waves compound Lu5Ir4Si10. The use of ultrafast time-resolved optical pump-probe experiments, coupled with ab-anitio theoretical calculations of the electron-phonon coupling and the electronic structure, permits to shine new light on the nature of this transition which we identified as a structurally-driven Peierls transition [2]. The Chapter 5 (6) is dedicated to the investigation of the high-temperature copper-oxide superconductor, La2−x Srx CuO4, for different doping levels; the experiment was carrying out at the SLS on the Micro-XAS beamline, By using a transient temperature model and comparing our experimental results with temperature-dependent density of states calculations, we report on the electronic temperature dependence of the electron-phonon coupling constant (submitted to Phys. Rev. B).

EPFL2013

Computational studies for the description of electronic and optical properties for photocatalysis in Metal Organic Frameworks

Andres Adolfo Ortega Guerrero

Metal-organic frameworks(MOFs) are promising materials for photocatalytic applications. MOFs modular and porosity structure provides a platform to assemble photo-active and catalytic-sites building block units that can offer unique photo-physics. This feature is of great interest for H2 evolution photocatalytic applications. However, MOFs current photocatalysts do not meet the industrial need for their implementation as a technology due to performance limitations. Thus, elucidating and predicting the optical properties of MOFs will have wide implications in the development of MOF-based photocatalysts. Computational studies can be of great aid for the discovery of MOFs photocatalyst. Yet, this is a challenging task for computational chemistry given the complexity of the photophysical properties, the inorganic-organic nature, the number of atoms, and the unit cell size of MOFs. The principal goal of this thesis is the study MOFs photophysical properties for predicting their feasibility for photocatalytic applications. Density functional theory (DFT) and linear-response time-dependent DFT (LR-TDDFT) formalisms are used for the description of the light absorption, charge separation, and charge transfer properties of MOFs. We first address the dependence of the ligand in the UV/Vis optical absorption of porphyrin-based MOFs. The characterization of the excited states of the porphyrin ligands in MOFs requires an appropriate approximation for the description in periodic crystal MOFs. The selection of proper functionals and approximations within DFT/TDDFT calculations is necessary to overcome the erroneous description of properties like excitonic effects, optical transitions, and gap-renormalization. Later, we continue with the study of the charge separation in a porphyrin ruthenium-based MOF. We describe the importance of missing coordinated solvents anions in the metal node for the stability and charge transfer mechanism in the material. Within this study, we computed electron-hole interacting energy indicating a low electron-hole recombination rate. We next introduce a computational strategy to describing the long-lived electron-hole pairs and the long-rage charge transfer in MOFs. This description can be depicted by computing charge transfer numbers and the effective mass of carriers, respectively. This methodology can correctly predict the charge separation and the effective mass of 15 representative MOF structures promising for photocatalysis in agreement with the literature. Finally, we present an experimental and theoretical combined study investigation towards optimal photocatalytic hydrogen evolution reaction (HER) in MOFs. Isostructural pyrene-based MOFs with different transition metals allowed us a proper comparison. This study highlights the interplay between tunning electronic properties and crystal morphology on the photocatalytic HER performance of the MOFs. These results presented in this thesis can be exploited and transfer to the study of other MOFs for HER photocatalysis.

EPFL2021

The Interplay Between Structural and Electronic Degrees of Freedom in Superconductors

Mathieu Julien Gino Cottet

EPFL2013

Computational studies for the description of electronic and optical properties for photocatalysis in Metal Organic Frameworks

Andres Adolfo Ortega Guerrero

EPFL2021

Electronic challenges for postal services

The Interplay Between Structural and Electronic Degrees of Freedom in Superconductors

Computational studies for the description of electronic and optical properties for photocatalysis in Metal Organic Frameworks

The Interplay Between Structural and Electronic Degrees of Freedom in Superconductors

Electronic challenges for postal services

Computational studies for the description of electronic and optical properties for photocatalysis in Metal Organic Frameworks