Missions

Applications in the field of THz radiation cover a very broad spectrum, ranging from monitoring the irrigation of agricultural crops and non-destructive testing of welds in the automotive industry, and now extending to high-frequency telecommunications beyond 6G.
Unlike visible or near-infrared optics in optical telecommunications, very few active optical elements are currently available in this spectral range, and the field of research is wide open.
This project aims to study new materials based on ferrimagnetic oxides whose spin properties respond to THz excitations both as active materials (e.g. for THz wave manipulation) and in the field of spin-to-charge conversion for the creation of broadband THz emitters (e.g. [1]). An indication of the presence of an ultrafast photo-induced spin current can already be observed from a measurement of spin dynamics [2]. Such strong spin signals have been observed for a variety of insulating oxides, such as garnets, orthoferrites [3], spinel systems and hexaferrites [4]. Consequently, all oxides can generate photo-induced spin currents.
Research within this project focuses on the growth of orthoferrite thin films, on photoinduced ultrafast charge and spin currents, and on the dynamics in insulating orthoferrite and hexaferrite thin films for spin current conversion, such as THz emitters.
In this research project, thin films based on iron oxide (orthoferrites) will be synthesized and studied for their potential to generate charge and spin currents using ultra-short femtosecond optical pump pulses. The targeted rare earth iron-based perovskite material will be synthesised in situ using a state-of-the-art pulsed laser deposition system. Key characterisations include X-ray diffraction for structural properties and temperature-dependent magneto-optical properties to evaluate the basic magnetic properties of the materials, such as saturation magnetisation and Curie temperature. The materials will then be studied for their transient physical properties such as absorption and reflectivity using the instrumentation available in the laboratory, in particular a state-of-the-art ultrafast spectroscopy system, HARPIA, marketed by LightConversion. Transient absorption spectroscopy of rare earth orthoferrites and hexaferrites will determine both the electronic band structure and the dynamics of the photoinduced charge current. The associated spin dynamics will be studied by time-resolved magneto-optics and THz spectroscopy, both internally and in collaboration with partners in this project.
This project is part of the France 2030 programme of excellence, the PEPR SPIN in spintronics, within the framework of the ANR MoxSpin project.
[1] T. S. Seifert et al., Appl. Phys. Lett. 120, 180401 (2022).
[2] T. Moriyasu et al., in Ultrafast Phenomena XIX, edited by K. Yamanouchi et al. (Springer International Publishing, Cham, 2015), pp. 653–656.
[3] A. V. Kimel and A. K. Zvezdin, Low Temperature Physics 41, 682 (2015).
[4] H. Ueda et al., Phys. Rev. Res. 4, 023007 (2022).

Activités

The candidate will work with a UHV laser deposition facility, a magneto-optical spectroscopy facility, and techniques such as time-resolved optical absorption, THz spectroscopy and time-resolved magneto-optics. The postdoctoral researcher will grow thin films using pulsed laser deposition and will work in particular on the epitaxy of perovskite films. He or she will use ultrafast optical and magneto-optical facilities as well as time-resolved spectroscopy. Basic programming skills are welcome as the facility is currently implemented with Python.

Compétences

The candidate should have a good understanding of materials growth, magnetism, optics, and solid-state physics. Solid experience in optical spectroscopy and related experimental techniques is also recommended. Good skills in programming, interfacing, data processing, and analysis (preferably using Python) are highly appreciated. English is the working language of the team. We are looking for a postdoctoral researcher who enjoys experimental work within an intercultural team, has good communication skills and develops a meticulous approach with attention to detail.

Contexte de travail

The postdoctoral researcher will work in the Materials and Light Department at the Rennes Institute of Physics and will also be a member of the Nanosciences and Materials Department.
The Materials and Light team is currently a major player in the Franco-Japanese international laboratory IRL DYNACOM, involving French and Japanese universities (CNRS, University of Rennes, University of Tokyo, University of Tohoku), and is globally recognised in the field of ultrafast science. The working environment is multicultural and international.
Our research focuses on the growth of functional magnetic oxides for spintronics, ultrafast out-of-equilibrium phenomena in materials and molecules using optical and X-ray techniques with temporal resolution from femtoseconds to picoseconds.
Further information is available on the website:
https://ipr.univ-rennes.fr/en/materials-and-light-departement

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.