Severo Ochoa Programme 2014-2018 RESEARCH AREAS: ICT

Information and communication technologies have a direct impact on virtually all aspects of modern society. The new working principles emerging from the study of materials at the nanoscale will enable faster, smaller and more energy-efficient devices. Our vision in this area goes beyond the conventional charge-manipulated-by-electrical-input paradigm to include the exploration of spin, phonons and photons as alternative state variables, and their manipulation using mechanical stress, light and heat.

Highlights in this work package so far include:

In collaboration with researchers from MESA+ and Cornell University, the ICN2 has developed the world’s first MEMS device based on inverse flexoelectricity, a process whereby applying voltage to a dielectric material causes it to bend with a curvature that is inversely proportional to the thickness of the film cubed. These micromachines have been made on silicon substrates, a prerequisite for their subsequent real-world use, and promise unprecedented energy savings and improved functionality.

We have also combined flexoelectricity with piezoelectricity in a novel device concept which we have dubbed a “strain diode”, where the curvature of the bend depends on the polarity of the voltage applied.

The ICN2 offers insights at the very forefront of science’s understanding of graphene spintronic devices. Spintronic devices exploit the idea that the spin, and not just the charge, of subatomic particles like electrons can be manipulated and used to store and process data, at a fraction of the energy cost of conventional electronics. Graphene for its part can be manipulated to present extremely useful properties in this context.

ICN2 research groups lead theoretical and experimental studies within the European Commission’s Graphene Flagship, implementing largescale full-quantum simulations and novel experimental approaches that are shedding considerable light on the physics behind the spin dynamics unique to graphene. They have also developed new methods to explore and consolidate our current understanding of spintronic phenomena in general.

The ICN2 has theoretically determined the intrinsic limitations of the Seebeck coefficient in graphene produced by chemical vapour deposition (CVD), and identified its polycrystalline morphology as their origin. This is important because the complexity of the structural morphologies of graphene when produced on a large scale is a major roadblock to the development of high-performance optoelectronic devices able to take full advantage of the ground-breaking capabilities demonstrated at the small scale.

The study enabled interpretation of the photocurrent measurements performed at the Institute of Photonic Sciences (ICFO) on large CVD-grown graphene samples. It is the result of an international collaboration between the ICN2, ICFO and MIT, and has led to the development of a non-invasive optoelectronic technique for probing the optical and electronic features of graphene devices at the nanoscale.