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In-situ spectroscopy of oxide heterostructures

Applicant Baumberger Félix
Number 177006
Funding scheme R'EQUIP
Research institution Département de Physique de la Matière Condensée Université de Genève
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Condensed Matter Physics
Start/End 01.06.2018 - 31.05.2020
Approved amount 520'000.00
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Keywords (9)

Oxide interfaces; STM; Molecular Beam Epitaxy; Correlated electron systems; Rashba effect; ARPES; Two-dimensional electron gas; Quantum confinement; RIXS

Lay Summary (German)

Lead
Synthetische Materialien, aufgebaut aus atomar dünnen Schichten, haben enormes Potenzial für Anwendungen in Sensorik und Elektronik. Dazu muss man allerdings die Energieniveaus von Elektronen in solch künstlichen Materialien verstehen. Spektroskopische Methoden können diese Energieniveaus direkt messen und spielen daher eine herausragende Rolle bei der Eingrenzung verschiedener theoretischer Ansätze zur Beschreibung solcher Materialien.
Lay summary

In-situ Spektroskopie von Übergangsmetalloxid Heterostrukturen

Lead

Synthetische Materialien, aufgebaut aus atomar dünnen Schichten, haben enormes Potenzial für Anwendungen in Sensorik und Elektronik. Dazu muss man allerdings die Energieniveaus von Elektronen in solch künstlichen Materialien verstehen. Spektroskopische Methoden können diese Energieniveaus direkt messen und spielen daher eine herausragende Rolle bei der Eingrenzung verschiedener theoretischer Ansätze zur Beschreibung solcher Materialien.

Inhalt und Ziel des Forschungsprojekts

In diesem Projekt werden wir hochreine atomar dünne Übergangsmetalloxidfilme herstellen und sie im gleichen Vakuumsystem mit winkelaufgelöster Fotoemission (ARPES), einer der wichtigsten spektroskopischen Methoden der Festkörperphysik, untersuchen. Das Ziel ist direkt die Energie – Impuls Dispersion von elektronischen Zuständen in solchen synthetischen Materialien zu vermessen was wichtig ist um ein besseres theoretisches Verständnis ihrer Eigenschaften zu entwickeln.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Dieses Projekt wird Messdaten zur mikroskopischen elektronischen Struktur komplexer Oxidfilme generieren. Die Ergebnisse richten sich hauptsächlich an andere Forscher und werden es erlauben die Entwicklung von Übergangsmetalloxid Heterostrukturen voranzutreiben. Langfristig ist das Ziel solche Heterostrukturen in Elektronik und Sensorik einzusetzen.

Direct link to Lay Summary Last update: 24.01.2018

Responsible applicant and co-applicants

Associated projects

Number Title Start Funding scheme
160765 Mott Physics Beyond the Heisenberg Model in Iridates and Related Materials 01.01.2016 Sinergia
165791 Electronic properties of engineered low-dimensional systems 01.08.2016 Project funding (Div. I-III)
183300 High-resolution soft-X-ray ARPES facility at Swiss Light Source 01.03.2019 R'EQUIP
182695 The United Control over Charge Density and Spin State of Low Dimensional Electron System at Titanates 01.07.2019 Project funding (Div. I-III)
141828 NCCR MARVEL: Materials’ Revolution: Computational Design and Discovery of Novel Materials (phase I) 01.05.2014 National Centres of Competence in Research (NCCRs)

Abstract

We propose a new facility permitting in-situ angle resolved photoemission (ARPES) studies of the electronic properties of ultraclean oxide interfaces grown by molecular beam epitaxy (MBE). A particular focus of our work will be placed on engineered oxide surfaces and heteroepitaxial films down to one or two unit cells thickness. This range in film thicknesses is notoriously difficult experimentally, because conventional ex-situ probes commonly employed in the oxide electronics community are largely insensitive to the intrinsic properties of such films, which are often not stable at ambient conditions. However, understanding the limit of ultrathin films is essential for oxide heterostructures since their properties are very sensitive to structural distortions and because oxides often show very short screening lengths. Together, this renders much of the relevant physics very short range and thus highly localized at the interface. Studying such ultrathin films and engineered oxide surfaces we hope to discover new and possibly useful electronic phases stabilized uniquely at the interface of two oxides. If successful, this work will guide the design of new functional oxide heterostructures with tailored properties and thus make a significant impact in the emerging field of oxide electronics. In a related activity, we will investigate the microscopic electronic structure of thin films, bilayers and superlattices that already play an important role in the field of oxide electronics. This will provide much needed input to advance the understanding of their macroscopic properties. In the long-term, we envision using the facility for in-situ spectroscopic studies of research-lab all-oxide devices at a future nano-ARPES facility at the Swiss Light Source. In order to achieve these goals, we propose an experimental setup combining molecular beam epitaxy (MBE) with a spectroscopic scanning tunneling microscope (STM), X-ray photoelectron spectroscopy (XPS) and in-situ resistivity measurements. This facility will be permanently connected to the SIS beamline at the Swiss Light Source by an ultrahigh vacuum sample transfer system permitting state-of-the-art ARPES experiments on ultraclean oxide heterostructures. Employing a vacuum suitcase will allow transferring the same thin films and oxide heterostructures to the resonant inelastic X-ray spectroscopy (RIXS) instrument at the ADRESS beamline without exposure to air. As a probe of collective excitations within charge, orbital, spin and lattice degrees of freedom, RIXS ideally complements ARPES and the combination of the two techniques promises more profound insight into oxide heterostructures. The combination of oxide-MBE, STM and ARPES is new in Switzerland and presently available in very few laboratories around the world only. In particular, the integration of a low-temperature STM will be a crucial advantage over competing projects in the US and Asia, since it is uniquely powerful for the structural and electronic characterization of ultrathin films down to one or two unit cells thickness, where we see the most significant potential for relevant new discoveries.
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