Mapping energy carriers

How can we map out traps on a surface? Ferry Prins, Michael Seitz et al. have developed a curious strategy. First, they’ve injected a small population of excitons (gaussian shaped) in a 2D metal halide perovskite. The flow of these excitons through the material will be affected by the traps, kind of how the flow of water is affected by stones at the riverbed. Therefore, by visualising the flow of the excitons, you can “accurately map out the trap-state landscape in the perovskite lattice”.

This research, has been featured in the cover of Advanced Optical Materials. The picture has been done under the supervision of Ferry Prins and Michael Seitz.

Superconducting graphene

Graphene’s business card is running out of space. We’ve already seen it doing nearly every possible thing in condensed matter physics. And superconductivity was to be there. It was a matter of time.

Magnetism and superconductivity don’t get along… to put it politely. So when you add magnetic atoms into a superconductor, the superconducting order is locally broken and spectral features (called Yu-Shiba-Rusinov states) appear inside the superconducting gap. And this features are important because they might be useful for quantum computing. 

Ivan Bruhuega, has lead an important research collaboration involving several countries (Finland, France, Portugal and Spain), that has for the first time observed these Yu-Shiba-Rusinov states in graphene. The complexity of this experiment is hard to grasp. To begin with, you have to induce superconductivity in graphene. They’ve done this by growing nanometer scale superconducting Pb islands over it. And then, using scanning tunneling microscopy and spectroscopy they’ve visualized Yu-Shiba-Rusinov states in the graphene grain boundaries. Quite a challenge.

We made this picture to illustrate the experience and it’s been featured in the cover of Advanced Materials.

Single-molecule junctions and atomic contacts

Dr. Laura RincĂłn made her thesis defense in August 2009. The manuscript, titled Conductance, thermopower and thermal conductance measurements in single-molecule junctions and atomic contacts, is a study on the properties of these contacts in the context of molecular electronics and thermoelectricity. The defense was recently awarded with the Best Experimental Thesis GEFES award.

Dr. Rincón used this picture we made years ago on request of her PhD advisor Prof. Nicolás Agrait.

One electron at a time, please

There is plenty of room at the bottom. Well, plenty, yes, but not infinite. There is a limit on how small we can build things, or something that happens to be of great technological importance: how faint an electrical current can be. And we might have just found an answer to that.

Researchers from the Max Planck Institute for Solid State Research in Stuttgart, Ulm University and the Autonomous University of Madrid, have found the most basic way of producing an electrical current. They’ve coupled two atomic energy levels and then measured the electronic transference between them, one electron at a time. We’re talking about single electrons here, folks! As it can be imagined, this presents a huge challenge: a fine tunned scanning tunneling microscope, low temperatures, crazy stability, pure skill in the sample preparation, etc. You can read the paper published in Nature Physics, or a more comprehensive explanation here.

In science we know how sterile it is to discuss the possible technological breakthroughs this research can bring. But this is of no importance here, because this research is just beautiful, and that is enough. This is about witnessing the quantum world at its most basic form, without ornaments. Do you know these simplistic pictures of energy levels with a wavy line connecting them? These people have made that picture real.

And talking about pictures, we made this one on request of Dr. Christian Ast and Prof. Carlos Cuevas, to illustrate not the experiment, but how they feel about it. And as an illustrator, that’s also beautiful.

Long live the Nucleobase!

Multiple medical and biological sensors and targeted drug delivery are based in the functionalization of nanoparticles (NPs) with biomolecules. The role of the NPs is to enhance the optical response of the target surroundings. But this enhancement comes with a huge risk: this same radiation can severily damage DNA or RNA producing mutations.

Johannes Feist (UAM) together with groups from the University of Modena and the University of Munich, have studied in which conditions these NPs can act as a protection for the biomolecules (in this case Uracil) while being effective in their sensing/therapeutic function. And importantly, the results proposed in their research can be easily implemented with the current nanophotonic technology.

This paper, published in the Journal of Physical Chemistry Letters, has been recognized with the cover we designed together with the supervision of Dr. Feist.

Polariton condensates’ propagation.

Polaritons are versatile quasiparticles that could be at the core of new technologies, since polariton devices have been proposed, such as polariton lasers, optical gates, transistors, spin-based elements and integrated circuits. Yet, their propagation depends strongly on the geometry of the pathway laid for them.

In a recent paper, Luis Viña, Dolores MartĂ­n, et al. in a huge collaborative research (Madrid, Jena, WĂĽrzburg, Saint-Petersburg, Reykjavik and Saint Andrews) have analyzed the Impact of the energetic landscape on polariton condensates’ propagation along a coupler”, published in Advanced Optical Materials.



The amount of technical challenges involved in this research is hard to grasp: from the manufacture of the guides to the experimental measurements, that require literally “taking pictures of light”.

We did this picture that was featured in the cover of Advanced Optical Materials, under close supervision of Dolores Martín and Luis Viña.

 

Living electric wires

Materials scientists have for decades fantasized about using DNA as a structural element in electronic circuits. And for decades, the electrical properties of DNA have remain a mystery. Hundreds of different, controversial results have appeared in the literature… That ends today!

Researchers from Jerusalem, Tel Aviv, Michigan, Cyprus, Seville and Madrid, have reported the observation of “very high currents of tens of nanoamperes” through the backbone of DNA molecules. And what it is more interesting, this conduction occurs through great distances.

This observation has required the development of several techniques: a way to “grow” DNA attached to a gold nanoparticle and a way to trap this DNA using non uniform electric fields. In fact, these techniques are important on their own and whey could be the base for the development of a novel electronic bio sensor, highly sensitive to specific sequences of DNA of RNA.

We made this picture for Prof. Juan Carlos Cuevas (UAM) to illustrate these results published in Nature Nanotechnology.

 

Age and friction

Friction between surfaces is of great importance and it is at the core of numerous and different phenomena: from earthquakes to the development of microelectromechanical systems. A new work involving Germany, Switzerland and Spain have studied how the role of contact aging affects this friction. In particular, they’ve shown how thermally activated bond formation dramatically changes the friction strength over time.

They’ve published their findings in Physical Review X and its work, together with an image we designed for them (with the close supervision of Dr. Guilherme de Vilhena) appears today (3/12/19) in PR-X featured papers.

Join the FTMC!

Condensed matter physics is a big unknown, even for 2nd year physics students, let alone theoretical condensed matter physics. And funny enough, this branch of physics covers a huge percentage of the reality around us. It covers quantum physics, biophysics, fluids, materials, optics and acoustics, or low temperatures, just to name a few of its interests. Yet, few people know about it.

At the Theoretical Condensed Matter Physics department, at Universidad AutĂłnoma de Madrid are actively trying to fill this gap. They’ve made a video to inform and try to bring closer students and young people to this beautiful and amazing area of science. And Scixel happened to be around.

 

We’ve spend a great time working with them, discussing and creating this piece. Hope you like it and pay them a visit!

SAMS-4

SAMS-4 is the 4th edition of the Workshop on Scattering of Atoms and Molecules from Surfaces, which is organized every three years. Previous editions were held in Rehovot (Israel, 2010), Postdam (Germany, 2013) and Bergen (Norway, 2016) with great success. This year, organized by Prof. Daniel FarĂ­as the event will be held in Madrid.

Stefan Bilan kindly asked me to make a picture for their website. And this is what I did.