Research Topics

laboratoire d'optique
et de magnétisme
optimag

Sensors and Magnetization Dynamics

Sensors are omnipresent and essential to understand the issues related to the management and optimization of our equipment. They are also increasingly present in our individual and personal environment, in the fields of personal service, health or environmental quality control, etc.

Concerning electromagnetic sensors in particular, with their many fields of application, new concepts are developing for the development of non-invasive and non-destructive material investigation methods, such as AMR, GMR or GMI, for example.

After exploring the possibilities offered by giant magneto-impedance-based sensing elements (GMI), ferromagnetic microwires of cobalt-rich amorphous material (CoFeSiB) with high circumferential permeability, we focused on the feasibility of high-sensitivity magnetic field sensors based on sensing elements based on crystals of soft ferrimagnetic material, deposited by liquid phase epitaxy on a GGG substrate. Artificial periodic structures, created either by micro-gold bands or by engraving on the crystal surface, modify the propagation of surface magnetostatic waves, generated by microstrip lines or antennas. In the GHz range, the linear variation of the positioning of the absorption peaks as a function of the magnetic field suggests interesting potentialities in terms of measuring weak magnetic fields.

[EMSA 2014 - July 2014 - Vienna (Austria)]
EuroSensors 2015 - September 2015 - Freiburg (Germany) ]
[GDR Onde 2016 - May 2016 - Montpellier (France)]

Through a dynamic study using the broadband ferromagnetic resonance present in our laboratory, we were able to demonstrate the unidirectional nature of the α parameter in exchange-coupled Py/NiO magnetic nanostructures. The originality of this result lies in the fact that the unidirectional nature had neither been demonstrated nor proposed by the international community[Phys. Rev. Rapid. Com. 2010]

We have also demonstrated the effect of low dimensionality on the dynamics of magnetization, particularly on the gyromagnetic ratio, in ultra-thin layers of CoFeZr. [Eur. Phys. Lett. 2016]