Ferroelectric control of Rashba states – CONTRABASS

Spintronics devices involve ferromagnetic elements with high switching energies. Contrastingly, the polarization of ferroelectrics can be easily switched by an electric field, at energies typically 1000 times lower. Combined with high spin-orbit coupling elements, ferroelectrics have also a natural potential to generate a strong Rashba effect, which could allow obtaining an electrically-switchable, highly efficient spin-charge interconversion. The CONTRABASS project gathers five partners with complementary expertise in metal spin-orbitronics, oxide spintronics and spin-resolved photoemission, with the aim to demonstrate the ferroelectric control of the charge-spin conversion in Rashba heterostructures, and to explore its potential for applications. Two partners have recently obtained very important preliminary results, demonstrating the ferroelectric control of the conversion in a Al/STO 2D electron gas (2DEG) at low temperature. The conversion rate is perfectly remanent at zero field, and can be modulated in sign and amplitude up to ±60 nm, which is two order of magnitudes larger than what can be obtained in heavy metals. At the fundamental level, the ambition of CONTRABASS is to merge the fields of ferroelectricity and spin-orbitronics, and thus to reveal novel states of matter arising from the entanglement of several degrees of freedom (charge, spin, orbital and lattice). CONTRABASS has the potential to impact the fields of spintronics, ferroelectricity, multiferroism, oxide electronics and quantum materials. In particular, in spintronics the CONTRABASS project will allow replacing the ferromagnetism by ferroelectricity as the source of remanence, thus pushing the frontiers of knowledge towards directions which will fuel technology in the longer term. At the cross-road between spintronics, ferroelectricity and quantum materials physics, CONTRABASS will thus pioneer a new realm in spintronics, where spin currents can be generated, manipulated and converted by electric fields in a non-volatile way.