Merging nanoporous materials with energy-efficient spintronics
This Project aims to integrate engineered nanoporous materials into novel energy-efficient spintronic applications. Magnetic storage and magneto-electronic devices are conventionally controlled by means of magnetic fields (via electromagnetic induction) or using spin-polarized electric currents (spin-transfer torque). Both principles involve significant energy loss by heat dissipation (Joule effect). The replacement of electric current with electric field would drastically reduce the overall power consumption. Strain-mediated magneto-electric coupling in piezoelectric-magnetostrictive bilayers might appear a proper strategy to achieve this goal. However, this approach is not suitable in spintronics because of the clamping effects with the substrate, need of epitaxial interfaces and risk of fatigue-induced mechanical failure. The exciting possibility to control ferromagnetism of metals and semiconductors directly with electric field (without strain) has been recently reported, but most significant effects occur below 300 K and only in ultra-thin films or nanoparticles. This Project tackles the development of a new type of nanocomposite material, comprising an electrically conducting or semiconducting nanoporous layer filled with a suitable dielectric material, where the magnetic properties of the metal/semiconductor will be largely tuned at room temperature (RT) by simply applying a voltage, via electric charge accumulation. The porous layer will consist of specific alloys (Cu-Ni or Fe-Rh) or oxide diluted magnetic semiconductors, where surface magnetic properties have been recently reported to be sensitive to electric field at RT. Based on these new materials, three technological applications are envisaged: electrically-assisted magnetic recording, voltage-driven switching of magnetic random-access memories and spin field-effect transistors. The obtained results are likely to open new paradigms in the field of spintronics and could be of high economic transcendence.