Ferromagnetic / Multiferroic
The control of magnetism by the electric field alone is an old scientific challenge that has attracted renewed interest over the past decade or so. Electrically controlled magnetism is both a fundamental subject of condensed matter physics and opens up perspectives towards devices requiring low activation energy and allowing better miniaturization. Such a control can be achieved using multiferroic (MF) materials. We process our samples at OPTIMAG by magnetron sputtering. The reversal of magnetization is studied using a vector magnetometer (VVSM) developed at the Laboratory
In 2010, we were the first international research team to have developed polycrystalline BFO/F (F=Py) heterostructures by sputtering coupled by exchange[J. Appl. Phys. 2011 and 2012 and T. Haugel Thesis Brest 2013].
Recently, we have shown the dominant role of spin pumping (Pt buffer) and exchange coupling in the evolution of the gyromagnetic ratio and magnetic relaxation with BFO thickness in these heterostructures[J. Phys D 2016]
In addition, the detailed study of hysteresis cycles at room temperature revealed the presence of magnetic frustration leading to irreversible angular drag. Finally, we have highlighted a distribution of blocking temperatures in these systems[J. Richy - Thesis Univ. Brest 2016]
Currently we are studying the influence of "parasitic" phases on the exchange coupling in our systems[Colloque Louis Néel 2017]
Ongoing thesis
Financing Brittany Region / University of Brest - Co-badging with the Physics Department of Johannesburg - South Africa
Walaa Jahjah "Multiferroic nanostructures intrinsic and extrinsic: towards electrical control of magnetic properties"
Collaborations :
University of Johanesburg
CEMES Toulouse
Institute of Physics of Rennes
