Seminar: Prof. Manuel Bibes - Ferroelectric control of Rashba states: towards non-volatile spintronics driven by ferroelectricity

After 50 years of exponential increase in computing efficiency, the technology of today’s
electronics is approaching its physical limits, with feature sizes of just a few nm. New schemes
must be devised to contain the ever-increasing power consumption of information and
communication systems, which requires the introduction of non-traditional materials and new state
variables. As recently highlighted, the remanence associated with collective switching in ferroic
systems is appealing to reduce power consumption 1 . A particularly promising approach is
spintronics, which relies on ferromagnets to provide non-volatility and to generate and detect spin
currents. However, magnetization reversal by spin transfer torques is a power consuming process.
This is driving research on multiferroics to achieve a low-power electric-field control of
magnetization, but practical materials are scarce and magnetoelectric switching remains difficult to
control. In this talk, we will propose an alternative strategy to achieve low-power spin detection
and generation, in non-magnetic systems combining ferroelectricity and Rashba spin-orbit
coupling 2 . We will focus first on oxide-based 2-dimensional electron gases (2DEGs) based on
ferroelectric SrTiO3 and show how both spin-charge and charge-spin conversion can be controlled
by ferroelectricity 3 . While these results were obtained at low temperature, we will describe our
current efforts to realize ferroelectric 2DEGs with high Curie temperature, and present room-
temperature operation with the ferroelectric Rashba semiconductor GeTe 4 . These observations
open the way to the electric-field control of spin currents and to ultralow-power spintronics, in
which non-volatility would be provided by ferroelectricity rather than by ferromagnetism.