New projects & Milestones

During 2020, the group worked in five EU Horizon 2020 projects:

• PHENOMEN, All-phononics circuits enabled by opto-mechanics, FET Open project, coordinated by Prof. Sotomayor.
• NANOPOLY, Artificial permittivity and permeability engineering for future generation sub wavelength analogue integrated circuits and systems, FET Open project.
• TOCHA, Dissipationless topological channels for information transfer and quantum metrology, FET Proactive project.
• NANOSMART, NANO components for electronic SMART wireless Systems, ICT project.
• D-SPA, Diamond-based nanomaterials and nanostructures for advanced electronic and photonic application, MSCA RISE project.

The group was also involved in two Spanish National Plan projects —namely, SIP (Surface and interface reshaped phonon propagation and phonon coupling to photons) and SMOOTH (Optomechanical devices based on self-assembled and active materials), with Dr Garcia as PI—, a “RIS3CAT Indústries del futur” project —PLASTFUN (Pilot plant for plastic parts with advanced functional surfaces), a regional project SGR, an international project La Caixa Foundation MISTI Global Seed Fund programme (Controlling Thermal Transport in Silicon and 2D Materials Nanostructures) with Dr Sledzinska as PI, and a project funded by the ICN2 Severo Ochoa Technology and Valorisation programme on Cooling Photonics, coordinated by Dr Jaramillo.

The Phononic and Photonic Nanostructures group achieved important research results during 2020, a selection of which is given below.

In the field of thermal transport at the nanoscale, we demonstrated the crossover from ballistic to diffusive regime using scanning thermal probe microscopy in suspended crystalline graphene layers. In suspended polycrystalline MoS2 layers, we showed that the thermal transport is determined by the size and orientation of the grains, which can be used to tune structurally the thermal properties. The role of disorder was studied in suspended membranes patterned with disordered 2-dimensional phononic crystals, demonstrating the importance of filling fraction and distribution of features to reduce the thermal conductivity by, for example, a factor of 15% from circular to non-circular disordered ones. Our work earned us an invitation to write the review 2D Phononic Crystals: Progress and Prospects in Hypersound and Thermal Transport Engineering, which appeared in Advanced Functional Materials.

In the hot topic of radiative cooling, the group reported 14-degree Celsius cooling at ambient temperature using the sky as heat reservoir and the concept of surface-phonon polaritons. This earned Drs J. Jaramillo Fernandez and A. Francone a COLLIDER project, to advance toward higher TRLs and eventually realise a device that could reach the market. The news was reported in the La Vanguardia newspaper, among other media outlets.

Our research in optomechanics, part of the EU FET Open PHENOMEN project, reached new heights with the demonstration of genuine synchronisation of optomechanical nanobeams by mechanical interaction, a result that earned the authors mentions in Physics World.

In addition, in collaboration with Dr D. Lanzillotti Kimura (CNRS), we obtained the generation and detection of acoustic phonons in topological cavities, as a first step in our experimental research on topological phonons.