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Atelier spintronique

Ferroelectric gates for non-volatile control of ferromagnetism in diluted magnetic semiconductors

par Igor Stolichnov
Ceramics Laboratory, EPFL - Swiss Federal Institute of Technology, Lausanne 1015, Switzerland

Multiferroic systems with coupled ferroelectricity and ferromagnetism attract a lot of interest in view of their potential applications in spintronics and memories. Recently we have demonstrated a structure in which the magnetic response in a Ga(Mn)As channel is modulated by the electric field of the poled ferroelectric gate. Such ferroelectric-ferromagnetic bilayer presents potential benefits of nonvolatile electrical switching, low operation voltage and a possibility to modulate the properties in nanoscale via the polarization domain engineering. In our experiments a widely-recognized incompatibility between ferroelectrics and III-V semiconductors has been solved by integration of a polymer ferroelectric in a FET configuration. Using this system we can control the magnetic channel with a ferroelectric gate that can be reproducibly switched with less than 10V. Magnetotransport and extraordinary Hall effect resistivity data signal a Tc shift associated with ferroelectric polarization switching of 7-9%. The unique combination of the ferroelectric polymer gate properties including relatively large spontaneous polarization and low dielectric constant suggests a possibility of further reduction of the operation voltage towards the 5V limit making the system compatible with the standard TTL circuitry.