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Spin waves imaging by electron holography (M/F)

This offer is available in the following languages:
Français - Anglais

Date Limite Candidature : lundi 23 mai 2022

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General information

Reference : UPR8011-NICBIZ-001
Workplace : TOULOUSE
Date of publication : Monday, May 2, 2022
Scientific Responsible name : Nicolas Biziere - Christophe Gatel
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

The field of magnonics consists of using spin waves (magnons) instead of electrons as “information carriers”. These elementary excitations of magnetic materials have many advantages. First of all, they allow to avoid losses by Joule effect linked to the circulation of charges and therefore to reduce the electrical consumption of the components. In addition, their wavelengths can be nanometric for frequencies of a few GigaHertz, unlike electromagnetic waves in a vacuum. This makes it possible to envisage many applications, in particular in the fields of radiofrequency telecommunications or fast information processing (BIG DATA), with a drastic reduction in the size of radiofrequency components. This topic is now integrated into the ITRS (International Technology Roadmap for Semiconductors) as an alternative to CMOS.

However, many questions remain unanswered for the integration of these components. In particular, the spatial profile of precession of stationary spin wave modes in nanostructures is still poorly understood and may be poorly described in some cases by analytical models. Thus, the development of new methods for imaging the precession of magnetization at the nanometric scale would allow a better understanding of the excitation of dynamical modes in nano-objects.
To achieve this goal, we propose to develop an original method based on electron holography. This method of imaging magnetization in electron microscopy has been used for many years to observe static states in nanostructures with spatial resolutions down to 1 nm. During this thesis we will develop this technique in order to observe the local dynamics of magnetization in nanostructures thanks to a quasi-static approach. The proof of concept will be carried out on model objects (network of pads, lines or magnonic crystals) fabricated on substrates adapted to the constraints associated with electronic microscopy.

During this thesis, the student will develop experimental methods for observing spin waves by electron holography on model systems. The characterization of the dynamic modes will be carried out by inductive technique within the laboratory and will make it possible to characterize the samples before the electron holography measurements. The results obtained will be used to develop analytical or numerical models to explain the spin wave spectra observed for the various objects. This thesis will take place within the framework of the ANR EHIS project, led by CEMES. Thus, the student will collaborate with the LPCNO of Toulouse in the context of the nano-manufacturing of nano-objects as well as with the LSPM of Villetaneuse to characterize their dynamic modes by Brillouin diffusion.

The candidate will address many areas of experimental physics in the field of magnetism. This ambitious project will allow the candidate to use the various platforms of the laboratory (radiofrequency measurements, electron microscopy, nano-fabrication in a clean room, etc.) while developing a new topic. It will also make it possible to understand other more general studies in microelectronics, in a field that is booming worldwide but not very present in France.

The candidate must hold a Master 2 or an engineering degree, with a speciality in physics of matter and / or nano-physics. The candidate will have to show initiative and autonomy for a highly experimental and multidisciplinary subject.

Work Context

Laboratory : Centre d'Elaboration des Matériaux et d'Etudes Structurales (CEMES), 29 rue jeanne Marvig, Toulouse.
Team : Matériaux et dispositifs pour l'Electronique et le Magnétisme (MEM) – Interférométrie in situ et instrumentation pour la microscopie électronique (I3EM)
topics : nanomagnetism - electron holography - growth of materials

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