Hedgehog spin textures

Magnetic skirmions are quasiparticles which present extended configurations (or textures) of spins and their physics are of great interest since they could be used in spintronics as sensors or memory storage devices. Its manipulation and tailoring is thus of great importance.

In a recent work published in Nanoscale, a group led by Prof. Agustina Asenjo, report the stabilization of half hedgehog skyrmionic configuration in permalloy hemispherical nanodots, induced by the stray field of the MFM probe.

As the first author, Eider Berganza, explains, “this is a remarkable achievement due to soft magnetic nature of the permalloy and the absence of the choice of the material, which does not present magnetocrystalline anisotropy or Dzyaloshinskii–Moriya interaction, considered as necessary ingredients for the nucleation of skyrmions”.

 

This research, has been a huge collaborative effort that involved sample preparation, measurements and theoretical micromagnetic simulations in Spain, Germany and the US.

This image we did under the supervision of Eider Berganza and Miriam Jaafar (ICMM-CSIC) has been featured in the Cover of Nanoscale. Personally, has been the apex of a long and beautiful collaboration with old friends.

 

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 Martín, et al. in a huge collaborative research (Madrid, Jena, Würzburg, 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.

 

Sound Vortices

At Phonometa (Christensen’s Research Group), they’re specialists in physical acoustics and they’re finding acoustic analogues to an amount of physical processes.

In their last published work they show that, in Dr. Christensen own words “a Majorana‐like bound state can be engineered in artificial acoustic lattices thanks to a Jackiw–Rossi vortex, which is the analog of a topological superconductor vortex. Such vortex is created by introducing a Kekulé texture to the man‐made lattice of rigid cylinders. We also show how this binding mechanism can be well explained by a topological pumping process comprising adiabatic variations of the cylinder radii, which concentrates strong acoustic energy to the lattice center as shown in the cover image”.

This picture we made to illustrate the process, and under close collaboration with Dr. Johan Christensen and Dr Penglin Gao, was featured in the front cover of Advanced Quantum Technologies.

Covalent organic frameworks

Covalent organic networks are usually synthesized on noble metal surfaces. It is widely understood that these metals have strong catalytic abilities. However, it is of great interest the use of nonmetallic surfaces in these kind of reactions.

At the NanoPhysics Lab (CMF, Gipuzkoa) they’re studying one of these routes to obtain covalent molecular systems on non-metallic substrates. In particular they’ve managed to understand and improve the synthesis of nanoribbons on TiO2 surfaces. They show that highly reduced surfaces (in opposition to stoichiometric TiO2) increases the reaction yield and improved polymer length.

We did this picture to artistically illustrate the process under the close supervision of Dr. Celia Rogero.

Graphene Design

The level of control chemistry is reaching in the synthesis of graphene is mind-blowing. At the Department of Physics in Basel University, together with the University of Bern, Warwick and Lancaster, nitrogen-doped porous graphene nanoribbons (N-GNRs) were synthesized for the first time.

These N-GNRs are ladder-like molecules whose crystal lattice contains both periodic pores and a regular pattern of nitrogen atoms. And interestingly, these molecules don’t behave as conductors, as graphene does, but as semiconductors, making them very attractive in electronic applications.

We did this picture to illustrate the synthesis of the N-GNRs on request of Prof. E. Meyer and under the close supervision of Dr. Shi-Xia Liu.

 

On circulenes, flatness and butterflies.

Circulene is a polycyclic aromatic hydrocarbon molecule composed by eight benzene rings. Because of geometric demands, the molecule adopts a saddle-shaped structure.This family of molecules, made of hexagonal and pentagonal rings are been studied for their promising applications in organic semiconductors, organic light-emitting diodes and liquid crystalline materials.

Prof. Shingo Ito et al. have just described the first example of a circulene bearing six hexagons and two pentagons which happens to have unique electronic structures, and intrinsic properties. In particular, they’ve proved this circulene to adopt a planar configuration.

This research, published in the Journal of American Chemical Society (JACS), was featured on the cover. The image was made under close supervision of Prof. Shigeky Kawai and Prof. Shingo Ito.

 

Glowing Lanthanides

It’s not the first time we bring these people to our website, and there are several reasons for that. First of all, they keep hiring us to make cool images for them. But the main reason is that they are doing amazing work in the field of chemical sensors.

These time Dr. Juan Cabanillas-Gonzalez and Dr. Jose Sanchez Costa, both at IMDEA Nanociencia (Spain) bring us “A novel gas sensing mechanism exploiting lanthanide luminescence modulation upon NO2 adsorption”. To make a long story short, this is a crystal that glows beautifully when NO2 is around.

This has not only useful practical applications in the detection of NO2 market; it would make a beautiful luminescence displays without requiring expensive electronics. “But it also provides understanding of the nature and effects of NO2 interactions within the MOFs and the signal transduction mechanism.” You can read more about it in their recent article.

The picture we did to illustrate this experiment was featured on the cover of the Journal of Physical Chemistry Letters.

 

 

Field Effect, now in 2D!

Despite his age, Dr. Mario Lanza has a long experience and deep knowledge on the physics and development of micro and nanoelectronic devices. In this recent article he an his coworkers discuss “the main challenges and potential solutions towards the fabrication of field effect transistors with 2D semiconducting channels”. In particular, there is a useful analysis on how this technology, now dealing with sizes that approach the interatomic distances, could be implemented in the current semiconductor industry.

This picture we did for him was featured on the cover of Advanced Functional Materials.

Quantum coherence stability

Quantum technologies building on solid-state spin systems, as those used in quantum computing and quantum internet, require unprecedented levels of stability. Even small fluctuations in ambient magnetic field messes up with the coherence time of these systems. So for these technologies to have any future we first have to learn how to stabilize and protect individual quantum ensembles. Doctor (congratulations on that) Johannes Koelbl at Basel University, has spent quite some time dealing with this challenge.

 

In this picture we made for him it is shown a Nitrogen-Vacancy center spin embedded in a diamond mechanical cantilever. As Dr. Koelbl explains: “To enhance its coherence properties, the spin is driven by both a time-varying strain field and microwave magnetic fields. The strain field is caused by harmonic oscillations of the cantilever, while the nearby wire serves as a near-field microwave source. Optical manipulation allows detecting the improved spin properties.”

He has chosen this picture to appear in the cover of his thesis manuscript.

Weighing tumorigenic cells

One of the last papers published by BioNanoMechanics Lab mixes biology, medicine, mechanics and optics. They have developed an efficient method to tell tumorigenic cells from healthy ones using mechanical and optical techniques. This group of researchers seems to be truly committed with the removal of the border between physics and biology.

The resonance frequency of an object ( ωf ) is amazingly sensitive to nearly everything, and in particular, to changes in mass of the object. Now imagine you built a very small glass capillary tube, you fill it with water with cells suspended in it. In this conditions, ωf  will depend somehow in the mass of the cells. Now lets say, tumorigenic and healthy cells have different masses: there you have it! Your oscillating microcapillary tube is now a cancer detector.

Of course it is not that easy. To be sure they are measuring single cells and not clusters of cells or other suspended elements, they’ve added an optical probe, that produces, together with the mechanical data, a simultaneous optical measurement.

In summary, they’ve developed a novel, fast, efficient and beautifully ingenious way to detect tumorigenic cells.

This picture we did under the supervision of Montserrat Calleja and Alberto Martín was featured on the cover of ACS Sensors in December 2019.