We are delighted to welcome Dr Manuel Bibes to the school as part of our 2024-25 Sir Harrie Massey Colloquia Series.

Dr Bibes will deliver a lecture titled 'Ferroelectric control of spin-charge interconversion for ultralow power electronics'. An abstract and biography can be found below.

Abstract:

After 50 years of exponential increase in computing efficiency through aggressive scaling down to feature sizes smaller than 10 nm, the technology of today’s electronics (complementary metal oxide semiconductor CMOS) is approaching its limits. Most significantly, new schemes must be devised to contain the ever-increasing power consumption of information and communication systems that already amounts to 11% of the world’s electricity and is expected to grow by a factor 2 to 5 by 2030¹. This requires a paradigm shift, with the introduction of new state variables – physical quantities that store and transmit the logic state – and non-traditional materials, derived from fundamental advances of condensed matter physics. In particular, resorting to ferroic systems with collective switching behavior and non-volatility appears essential to bring memory into logic and alleviate energy-costly on-chip data transfer².

One particularly promising approach for information processing is spintronics, a very active field of research that involves the intimate interaction of the magnetic and electronic structure with spin currents^3,4. While classical spintronics has traditionally relied on ferromagnetic metals as spin generators and spin detectors, a new approach called spin-orbitronics exploits the interplay between charge and spin currents enabled by the spin-orbit coupling (SOC) in non-magnetic systems⁵. An important advantage of spin-orbitronics is that it allows the generation of pure spin currents from charge currents and vice versa from the (direct and inverse) spin Hall and Edelstein effects. However, the conversion efficiency and its sign are inherently set by the materials’ electronic structure, hampering the development of spin-orbit systems as agile sources and detectors of spin current able to replace ferromagnets.

In this talk, we will argue that combining ferroelectricity and spin-orbit coupling may lead to switchable sources and detectors of spin currents that will be free from ferromagnets, non-volatile and operate by electric fields only. Such systems would open the way to a new generation of logic-in-memory devices that, when assembled into architectures, could strongly reduce the computing energy compared to CMOS technology. We will present our progress in the control of spin-orbit effects and spin-charge interconversion using ferroelectricity. We will show results on three different systems namely (i) ferroelectric oxide-based two-dimensional electron gases⁶, (ii) the ferroelectric Rashba semiconductor GeTe⁷ and (iii) bilayers combining oxide ferroelectrics with transition metal dichalcogenides. We will discuss challenges and pathways to bring these physical concepts into technology for ultralow power computation.

1. Andrae, A. et al. Challenges 6, 117 (2015).
2. Manipatruni, S. et al. Nature Phys 14, 338 (2018).
3. Žutić, I. et al. Rev Mod Phys 76, 323 (2004).
4. Sinova, J. et al. Nature Mater 11, 368 (2012).
5. Trier, F. et al. Nat Rev Mater 7, 258 (2022).
6. Noël, P. et al. Nature 580, 483 (2020).
7. Varotto, S. et al. Nature Electron 4, 740 (2021).

Biography:

Manuel Bibes is a CNRS Research Director at the Laboratoire Albert Fert in Palaiseau, France. After a double PhD degree in France and Spain with a thesis on manganite interfaces (ICMAB Barcelona, 2001) he became a CNRS Researcher in 2003. Bibes has pioneered research lines on multiferroics, ferroelectric tunnel junctions and explored novel routes for the electrical control of magnetism and spin transport in oxide architectures. Bibes is the laureate of three ERC grants and a Highly Cited Researcher. He has received several awards including the Descartes-Huygens Prize in 2017 and the EuroPhysics Prize in 2022.

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