Energy Efficient Future Generation Electronics Based on Strongly Correlated Electron Systems

Abstract

Three major developments in three decades are quietly changing the whole spectrum of ‘electronics’ (as it is conventionally known) making it ready for a major revolution. At the heart of this lies the ‘electronics based on strongly correlated electron systems’. The broad canvass of ‘strongly correlated electron systems’—especially the ones assuming importance for future generation electronics—covers primarily transition metal ion based complex oxide compounds exhibiting superconductivity at a record high temperature (cuprate superconductors); gigantic change in electrical resistivity under tiny magnetic field (CMR manganites); and coexisting ferroelectric and magnetic orders within a single phase with an extraordinary cross-coupling (multiferroics). Thanks to these developments, apart from charge of an electron, its spin and orbital degrees of freedom are now being shown to offer tremendous manoeuvrability for developing not just electronic but spintronic and orbitronic devices as well. Larger coherence length and stability of spin and orbital spectra can be exploited for bringing functionalities hitherto unknown. Using up and down spins and different patterns of orbital occupancy of the electrons, it is now possible to design and develop spintronic and even orbitronic devices by exploiting esoteric effects such as spin-transport, spin-tunnelling, spin-Hall, spin-Seebeck or switching of orbital orders under optical illumination. These nanoscale devices are energy efficient and ultra-sensitive. They are expected to perform more complex jobs in a vast arena which includes even bio-electronics. In this article, we introduce the area of strongly correlated electron systems and explore the advancements already made and possibilities emerging in developing future generation electronic-spintronic-orbitronic devices based on complexities which till now stubbornly defied complete understanding in spite of intense efforts worldwide—a classic example of which is the mechanism of high temperature cuprate based superconductors.