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High resolution spectroscopy of strongly correlated electron systems and artificial structures at surfaces

Applicant Grioni Marco
Number 182035
Funding scheme Project funding (Div. I-III)
Research institution Institut de Physique des Nanostructures EPFL - FSB - IPN
Institution of higher education EPF Lausanne - EPFL
Main discipline Condensed Matter Physics
Start/End 01.12.2018 - 30.06.2021
Approved amount 791'093.00
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Keywords (5)

ARPES; low-dimension; time-resolved; synchrotron radiation; electronic properties

Lay Summary (French)

Lead
Nous utilisons des techniques spectroscopiques avancées telle que la photoémission résolue en angle (et en temps): tr(ARPES, pour déterminer les propriétés électroniques de nouveaux matériaux d'intérêt fondamental et pour des applications futures. Parmi les systèmes que nous étudierons on peut mentionner les composés des métaux de transitions à fortes corrélations électroniques, les matériaux à basse dimensionnalité, les isolants et sémimétaux topologiques.
Lay summary
Sujet et Objectives

La spectroscopie de photoémission se base sur l'effet photoélectrique, dont l'interprétation théorique représenta une  étape fondamentale dans le développement de la mécanique quantique, et pour laquelle A. Einstein reçu le prix Nobel. Les électrons éjectes d'un solide par un faisceau de lumière ultraviolette garde mémoire de leur état à l'intérieur du matériau. En étudiant leurs propriétés - l'énergie, la vitesse - nous pouvons sonder directement leur état dans le solide. La connaissance de la structure électronique nous permet de comprendre les propriétés physique du matériau, et de prédire les propriétés de nouveau matériau artificiels.

Moyens expérimentaux

La détermination précise des propriétés des états électroniques demande l'utilisation de sources de lumière sophistiquées et puissantes. Nous utiliserons le rayonnement synchrotron dans plusieurs laboratoires en Europe et ailleurs, où nous obtenons un accès à la suite d'une sélection compétitive des projets. Le rayonnement synchrotron nous donne la possibilité de varier l'énergie des photons du domaine des UV jusqu'au rayons X.

Nous obtenons des information complémentaires sur la structure électronique par l'étude de la réponse ultrarapide - à l'échelle de la picoseconde - à une impulsion optique ultracourte. Dans ces expériences nous utilisons des impulsions UV générées par un puissant laser au laboratoire LACUS (Lausanne Center for ULtrafast Science) de l'EPFL.


Mots-clé

Nouveau matériaux; fortes corrélations; matériaux topologiques; propriétés électroniques; spectroscopie de photoémission; dynamique ultrarapide
Direct link to Lay Summary Last update: 28.09.2018

Lay Summary (English)

Lead
We exploit state-of-the-art spectroscopic techniques such as (time- and) angle-resolved photoelectron spectroscopy (tr)ARPES to determine the electronic properties of novel materials of fundamental interest and/or of interest for advanced applications.The systems we will study include transition metal compounds with strong electronic correlations or electron-lattice coupling, low-dimensional materials, topological insulators and semimetals.
Lay summary
Subject and Goals

Photoelectron spectroscopy is based on the photoelectric effect, whose theoretical explanation marked a milestone in the development of quantum physics, and earned A. Einstein a Nobel prize. Electron ejected from a solid by a monochromatic ultraviolet light beam retain memory of their state inside the material. By studying their characteristics - their energy, their velocity - we can directly probe their pristine state inside the solid. Knowledge of the electronic structure allows us to understand most of a material's properties, and to predict the properties of new artificial materials.

Experimental Tools

A precise determination of the properties of the electronic states requires the use of sophisticated and powerful light sources. We will exploit synchrotron radiation at various sources worldwide, where we gain access through competitive selection processes. Syncrotron radiation allows us to vary the energy of the photons from the UV up to the x-ray range.

We also gain complementary information on the electronic structure by studying the ultrafast (~ picosecond) response
to an ultrashort optical pulse. To this end we will use UV pulses generated by a powerful laser at the LACUS (Lausanne Center for Ultrafast Science) laboratory at EPFL

Keywords

Novel materials; strong correlations; topological materials; electronic properties; photoelectron spectroscopy; ultrafast dynamics


Direct link to Lay Summary Last update: 28.09.2018

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
162593 High resolution spectroscopy of strongly correlated electron systems and artificial structures at surfaces 01.12.2015 Project funding (Div. I-III)
160765 Mott Physics Beyond the Heisenberg Model in Iridates and Related Materials 01.01.2016 Sinergia

Abstract

This grant supports the operation of the Laboratory for Electron Spectroscopy of the Institute of Physics (LSE-IPHYS) of the EPFL. During the previous grant period, besides pursuing the science program, we have relocated our laboratory and commissioned a time-resolved photoemission (trARPES) instrument, as part of the Lausanne Center for Ultrafast Science (LACUS). In the next grant period we will follow two complementary lines of research. On one hand we will study equilibrium electronic properties of selected quantum materials, including cuprates, transition metal (TM) oxides, topological materials, layered TM dichalcogenides, 1D metals. Our main probe will be high-resolution angle-resolved photoemission (ARPES), both in-house and with synchrotron radiation. On the other hand, we will exploit trARPES to study the out-of-equilibrium dynamics and gain a complementary view, in the time domain, of the quasiparticles excitations. Pump-probe measurements will also allow us to probe transient phases and electronic states outside the Fermi surface, which escape detection by conventional ARPES. In consideration of the limited manpower and of the growth of the trARPES activities we will considerably scale down the resonant inelastic x-ray scattering (RIXS) part of our program, which has nevertheless yielded valuable results in the past.Our program relies on the IPHYS crystal growth laboratory, which provides us with high-quality, sometimes unique, single crystals. Equally important are the local theoretical support by O. Yazyev (DFT calculations) and F. Mila (correlated systems), and collaborations with M. Chergui for LACUS activities, and with IPHYS colleagues H. Rønnow, L. Forro, F. Carbone.We will again benefit from fruitful external collaborations: J. Chang (Zurich) on strongly correlated materials; E. Rotenberg and S. Moser (ALS, Berkeley), L. Moreschini (Cornell) for advanced ARPES synchrotron experiments, including the in-situ growth of thin film samples by pulsed laser deposition; D. Mihailovic (Ljubljana) on CDW compounds; F. Parmigiani (Trieste) and E. Springate (RAL) for time-resolved ARPES experiments. In theory: T. Giamarchi (Geneva); S. Biermann (Ecole Polytechnique); E. Canadell (Barcelona) for low-dimensional systems; F. Giustino (Oxford) on oxides; A. Rubio (Hamburg) and A. Marini (Rome) on trARPES.
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