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Spin-Charge Correlations in Magnetic van der Waals Materials

English title Spin-Charge Correlations in Magnetic van der Waals Materials
Applicant Schmitt Thorsten
Number 207904
Funding scheme Project funding
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Condensed Matter Physics
Start/End 01.06.2022 - 31.05.2026
Approved amount 668'324.00
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Keywords (7)

Resonant Inelastic X-Ray Scattering (RIXS); electronic structure; van der Waals materials; pump-probe spectroscopy; magnetic two-dimensional materials; low-energy excitations; spin-charge correlations

Lay Summary (German)

Lead
Die Eigenschaften von Quantenmaterialien, die Übergangsmetallatome enthalten, sind durch eine starke Kopplung zwischen Ladungs-, Orbital-, Spin- und Gitterfreiheitsgraden gekennzeichnet. Die große Vielfalt an funktionellen Eigenschaften von quasi-zweidimensionalen (2D) van-der-Waals-(vdW)-Materialien hat in letzter Zeit breite Aufmerksamkeit erregt. Die in solchen Materialien auftretenden Quanten-Vielteilchenphänomene ermöglichen Anwendungen in zukünftigen elektronischen und spintronischen Geräten. vdW-Materialien mit 3d-Übergangsmetallen mit magnetischer Ordnung und unterschiedlichen Transporteigenschaften eröffnen neue Möglichkeiten für hochgradig abstimmbare elektronische Bauelemente mit gekoppelten magnetischen Eigenschaften. Die Möglichkeit, dünne Schichten dieser vdW-Materialien bis zu einzelnen Monoschichten (MS) zu exfolieren, ermöglicht die Manipulation der elektronischen Struktur und des Magnetismus durch einfaches elektrostatisches «Gating».
Lay summary

Inhalt und Ziel des Forschungsprojektes

Die resonante inelastische Röntgenstreuung (Engl. RIXS) ermöglicht eine hochempfindliche Untersuchung der elektronischen und magnetischen Eigenschaften. Das Ziel des vorliegenden Projektes ist es, mit RIXS-Studien ein grundlegendes Verständnis der mikroskopischen Ladungs-Spin-Korrelationen von magnetischen 2D-Materialien als Funktion der Temperatur, der Anzahl der MSs, der elektrostatischen «Gate»-Spannung und nach Laser-Anregungen zu erlangen. Die elektronische Konfiguration und der Spinzustand dieser magnetischen 2D-vdW-Materialien werden bestimmt, um damit den Zusammenhang zwischen der elektronischen Struktur und dem Magnetismus herzustellen.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojektes

2D-Magnete erlauben Grenzflächenphänomene in vdW-Heterostrukturen zu konstruieren. Von einer breiteren Perspektive werden solche Studien die Anwendung von 2D-Magnetmaterialien in zukünftigen spintronischen Geräten im Zusammenhang der Informationstechnologie ermöglichen.
Direct link to Lay Summary Last update: 09.05.2022

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Associated projects

Number Title Start Funding scheme
189640 High-energy resolution spectrometer for SASE broadband Time-Resolved RIXS at Furka endstation 01.03.2021 R'EQUIP
160765 Mott Physics Beyond the Heisenberg Model in Iridates and Related Materials 01.01.2016 Sinergia
177006 In-situ spectroscopy of oxide heterostructures 01.06.2018 R'EQUIP
178867 Electron-Phonon Interactions in Rare-Earth Nickelates and Superconducting Cuprates 01.10.2018 Project funding
141828 NCCR MARVEL: Materials’ Revolution: Computational Design and Discovery of Novel Materials (phase I) 01.05.2014 National Centres of Competence in Research (NCCRs)
141962 Mott Physics Beyond the Heisenberg Model in Iridates and Related Materials 01.01.2013 Sinergia
141325 Coupled spin, charge and orbital dynamics of low-dimensional cuprates 01.09.2013 Project funding

Abstract

The properties of quantum materials containing transition metal atoms are characterized by strong coupling between charge, orbital, spin and lattice degrees of freedom. The broad variety of functional properties of quasi two-dimensional (2D) van der Waals (vdW) materials have recently received widespread attention. The quantum many-body phenomena arising in such materials enable emergent functionalities for applications in future electronic and spintronic devices, as well as for information technology. VdW materials with 3d transition metals possessing magnetic ordering and varying transport properties open up new possibilities for highly tunable electronic devices with coupled magnetic properties. The possibility to exfoliate thin layers of these vdW materials down to single monolayers (MLs) allows manipulating the electronic structure and magnetism by simple electrostatic gating. In addition, 2D magnets open the possibility to engineer interfacial phenomena in vdW heterostructures through stacking two layers under a twist angle and proximity effects.Resonant Inelastic X-ray Scattering (RIXS) is a powerful probe of the elementary excitations from the electronic ground state of quantum materials involving lattice, charge, orbital and spin degrees of freedom. With its ML sensitivity, RIXS is ideal to investigate the electronic structure changes and coupling effects between different degrees of freedom for bulk magnetic 2D vdW materials as well as for materials with ML thickness. The objective of the present proposal is to get in-depth fundamental understanding of the microscopic charge - spin correlations of magnetic 2D materials from RIXS studies as a function of temperature, number of MLs and electrostatic gate voltage. The electronic configuration and spin state of these magnetic 2D vdW materials will be determined in order to establish the relation between the electronic structure and magnetism and how this originates from the strong coupling between orbital and spin degrees of freedom. Furthermore, we will explore exotic emergent phenomena that may arise in vdW materials by electrostatic tuning. In work package 1 (WP 1) we will deal with antiferromagnetic (AF) vdW materials, while WP2 will address ferromagnetic (FM) vdW materials. The main class of AF 2D materials to be investigated are the insulating transition metal thiophosphates (TMPS3), which host different types of antiferromagnetism (AFM) with TM = Mn, Fe, Co and Ni down to 1-2 MLs. Of the semiconducting chromium tri-halides to be studied, CrCl3 is A-type AF, whereas CrI3 and CrBr3 are FM down to 1 ML, with the peculiarity of bilayer CrI3 being AF. The localized spin systems CrGeTe3 and CrSiTe3 as well as the itinerant metal Fe3GeTe2 are FM down to 1-2 ML. In WP 3 we probe the ultrafast dynamics of the magnetism and spin - charge interplay in transient states of photo-excited magnetic vdW materials by time-resolved RIXS studies. By pumping the 2D magnetic materials with ultrafast laser pulses above the band gap or in resonance with orbital modes, the recovery dynamics of the depleted magnetically ordered phases or the disentanglement of spin and orbital degrees of freedom will be studied. In summary, we will elucidate changes in the charge - spin correlations that are correlated with the magnetism for bulk and ML thick crystals of 2D magnetic materials with and without electrostatic gating. With pump-probe RIXS experiments, we will infer the switching behavior of these materials. On a wider perspective, such studies will enable the application of 2D magnetic materials in future spintronic devices.
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