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Femtosecond control of topological magnetic patterns

English title Femtosecond control of topological magnetic patterns
Applicant Carbone Fabrizio
Number 159219
Funding scheme Project funding
Research institution Institut de physique de la matière condensée EPFL - SB - ICMP
Institution of higher education EPF Lausanne - EPFL
Main discipline Condensed Matter Physics
Start/End 01.04.2015 - 31.03.2019
Approved amount 256'965.00
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Keywords (5)

electron vortex beams; femtosecond ; optical vortex beams; skyrmions; cryo-Lorentz-TEM

Lay Summary (Italian)

Lead
Controllo ultraveloce (femtosecondi) di un pattern magnetico topologico.
Lay summary

I materiali magnetici sono alla base di moltissime applicazioni. Vengono trovati nei dispositivi elettronici per immagazzinare informazione, nei sensori per misurare o produrre campi magnetici. La densità di informazione che può essere stoccata in un dispositivo basato su una memoria magnetica dipende dalla dimensione dei domini magnetici. L'orientazione dei momenti magnetici in questi domini viene letta da un dispositivo apposito e codifica l'informazione desiderata. La necessità di stoccare una quantità sempre maggiore di informazione in spazi sempre più' confinati ha portato la tecnologia ad un limite fondamentale, al di sotto del quale le interazioni tra due domini magnetici adiacenti sono sufficientemente forti da perturbare la loro orientazione relativa e per conseguenza distruggere l'informazione ivi codificata. Per superare questo limite, nuovi materiali sono stati proposti, nei quali la distribuzione dei momenti magnetici di spin è "protetta" da particolari condizioni al contorno. Questi sistemi sono ideali per stoccare informazione in uno spazio estremamente piccolo e in modo robusto. Questi piccoli domini si chiamano Skyrmioni, e sono stati osservati di recente grazie alla microscopia di Lorentz, che è una variante della microscopia elettronica. Questo ha permesso di fare fotografie di queste distribuzioni di spins e studiarne il loro arrangiamento statico. tuttavia, per poter comprendere e aprire la porta ad una loro possibile utilizzazione, è necessario poter accedere alla loro evoluzione dinamica. In questo progetto, proponiamo di osservare la dinamica di una rete di skyrmioni attraverso la microscopia di Lorentz risolta nel tempo. Questi esperimenti sono possibili solo nel nostro laboratorio dove un microscopio elettronico capace di risoluzione temporale tra i femtosecondi, nanosecondi e microsecondo e capace di scendere fino a 4 K di temperatura sul campione, è installato.

Direct link to Lay Summary Last update: 27.03.2015

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Stacking transition in rhombohedral graphite
Latychevskaia Tataiana, Son Seok-Kyun, Yang Yaping, Chancellor Dale, Brown Michael, Ozdemir Servet, Madan Ivan, Berruto Gabriele, Carbone Fabrizio, Mishchenko Artem, Novoselov Kostya S. (2019), Stacking transition in rhombohedral graphite, in Frontiers of Physics, 14(1), 13608-13608.
Attosecond coherent control of free-electron wave functions using semi-infinite light fields
Vanacore G. M., Madan I., Berruto G., Wang K., Pomarico E., Lamb R. J., McGrouther D., Kaminer I., Barwick B., García de Abajo F. Javier, Carbone F. (2018), Attosecond coherent control of free-electron wave functions using semi-infinite light fields, in Nature Communications, 9(1), 2694-2694.
Generation and control of an ultrafast electron vortex beam via chiral plasmonic near-fields
VanacoreGianmaria, Berruto Gabriele, MadanIvan, Pomarico Enrico, BiagioniPaolo, LambRay, McGroutherDamien, ReinhardtOri, KaminerIdo, BarwickBrett, LaroqueHugo, Grillo Vincenzo, KarimiEbrahim, Garcia de AbajoJavier, CarboneFabrizio, Generation and control of an ultrafast electron vortex beam via chiral plasmonic near-fields, in Nature Materials.
Laser-induced Skyrmion writing and erasing in an ultrafast cryo-Lorentz transmission electron microscope
G Berruto, I Madan, Y Murooka, E Pomarico, GM Vanacore, J Rajeswari, R Lamb, P Huang, Y Togawa, T. Lagrange, D McGrouther, HM Ronnow, F Carbone, Laser-induced Skyrmion writing and erasing in an ultrafast cryo-Lorentz transmission electron microscope, in Phys. Rev. Lett..
meV resolution in laser-assisted energy-filtered transmission electron microscopy
E Pomarico, I Madan, G Berruto et al, meV resolution in laser-assisted energy-filtered transmission electron microscopy, in ACS Photonics.

Collaboration

Group / person Country
Types of collaboration
prof. Barwick, Trinity College, USA United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Dr Marco Cantoni, CIME Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Dr Damien Mc Grouther, Kelvin Nanocharacterisation Centre/ University of Glasgow Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Prof. Ronnow, LQM EPFL Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Communication with the public

Communication Title Media Place Year
Media relations: print media, online media Controlling skyrmions with lasers EPFL web-page International 2018

Associated projects

Number Title Start Funding scheme
128269 The dynamics of chemical bonds by ultrafast electron diffraction 01.09.2010 SNSF Professorships
154492 filming the interaction of elementary particles in a fs-TEM 01.05.2014 International short research visits
157956 NCCR MUST: Molecular Ultrafast Science and Technology (phase II) 01.07.2014 National Centres of Competence in Research (NCCRs)

Abstract

Topological magnetic patterns are found in materials as well as nanostructures. in various compounds belonging to the B20 crystalline group, for example, the distribution of spins resulting from the strongly anisotropic magnetic exchange interaction shows typical pattern termed skyrmions which recently gathered a lot of attention. The reason for the interest in these magnetic objects is that they are topologically protected defects that behave underseveral aspects like point-like particles. They have a well defined spatial extent, they have quantized associated properties, they undergo phase transitions and can sense attractive orrepulsive potentials. Such a particle, the skyrmion, has a spatial extension of few tens of nm, thus potentially interesting for data storage applications where miniaturization is critical, and because of it microscopic nature it is of great interest for fundamental reasons ranging from elementary particle physics, where skyrmions were first discussed, and condensed matter physics. Recently, the physics of skyrmions and similar topological magnetic patterns has been investigated successfully by Transmission Electron Microscopy techniques. In a TEM, Lorentz microscopy enables the direct-space observation of magnetic object with nm resolution. Not only the spatial distribution of skyrmions can be looked at via TEM experiments, but quantitative information about the magnetic moments can be obtained by imaging directly the magnetic moment strength distribution down to atomic resolution. A great deal of effort is also currently devoted to the dynamical observation of these magnetic patterns. How do they react to external perturbations such as electric fields, magnetic fields, light irradiation, and temperature fluctuations. The complication of these study mainly residing in the difficulty of imaging magnetism with nm resolution in space and at the same time with resolution in time. In our laboratory at the EPFL, we implemented and characterized the first and only femtosecond cryo-Lorentz TEM in the world, thanks to which movies of magnetic systems can be obtained from the ms time-scale of conventional camera-rates, to microsecond, nanosecond and femtosecond, covering in a continuous fashion 12 decades in the time domain. Moreover, we recently developed the ability to photo excite samples with optical beams carrying orbital momentum, also called vortex beams, that favorably couple to chiral structures, such as the magnetic moment distribution in skyrmions. In this project, we propose to perform time-resolved cryo-Lorentz TEM experiments on different systems displaying magnetic topological patterns in different conditions with the aim of understanding critical parameters such as the mobility of these objects (stimulated by temperature, field or light), and ultimately providing a direct optical control of their properties with a carefully prepared excitation in terms of wavelength, polarization and chirality (via vortex beams).
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