News

Doc. dr. Matjaž Humar from the Department of Condensed Matter Physics at Jožef Stefan Institute, and researchers from UK, USA and Japan have published an article titled Whispering-gallery-mode sensors for biological and physical sensing in Nature Reviews Methods Primers. In the paper the authors introduce whispering-gallery-mode microcavities in different geometries, such as microspheres, microtoroids, microcapillaries and microrings. Whispering-gallery-mode microcavities are miniature micro-interferometers that use the multiple-cavity passes of light for very sensitive measurements at the microscale and nanoscale, including single-molecule and ion measurements. The authors describe sensing mechanisms, including mode splitting and resonance shift, and optomechanical and optoplasmonic signal transductions. Applications and experimental results cover in-vivo and single-molecule sensing, gyroscopes and microcavity quantum electrodynamics.

In an extensive study, Jeffrey C. Everts and Miha Ravnik from the Faculty of Mathematics and Physics at University of Ljubljana and the Department F5 of Jožef Stefan Institute examined the details of the coupling of ions and singular topological defects in complex nematic fluids (Phys. Rev. X 2021). The authors showed that topological defects in nematic electrolytes could perform as areas for local separation of electric charge, forming electrically charged cores of defect and in selected geometries also electrical multi-layers. These charge distribution are generalizations of electrical double layers known in isotropic electrolytes. In particular, they show that ions couple very efficiently with the defect cores through the mechanism of ionic solubility, and with the surrounding orientation field deformations through the mechanism of flexoelectricity. The work is a significant contribution towards understanding the electrostatic mechanisms in complex soft matter.

The physical behavior of anisotropic charged colloidal particles in nematic solvents is determined by their dielectric anisotropy. Together with the experimental group of Professor Ivan Smalyukh at University of Colorado Boulder the authors Jeffrey C. Everts and Miha Ravnik from the Faculty of Mathematics and Physics at University of Ljubljana and the Department F5 of Jozef Stefan Institute demonstrated anisotropic electrostatic screening for charged colloidal particles in nematic electrolytes. The electrostatic potential and pair interactions decay with an anisotropic Debye screening length, contrasting constant screening length for isotropic electrolytes. Charged dumpling-shaped near-spherical colloidal particles in nematic media are used as model systems, demonstrating competing anisotropic elastic and electrostatic effective pair interactions for colloidal surface charges tunable from neutral to high, yielding particle-separated metastable states (Science Advances 2021, DOI: 10.1126/sciadv.abd0662). The work was published in Science Advances and contributes to the understanding of electrostatic screening in nematic media.

Dr. Martin Klanjšek from the Condensed Matter Physics Department published a News & Views article entitled Singlets singled out in Nature Physics upon invitation by the editor. In this article, the author presents his view of the achievements of the article Emergence of spin singlets with inhomogeneous gaps in the kagome lattice Heisenberg antiferromagnets Zn-barlowite and herbertsmithite published in the same journal by the research group of prof. Imai from the McMaster University in Canada. They report on the gradual formation of spin singlets in two quantum magnets with kagome lattice, which is an important step in the resolution of the ground state of this archetypal magnet. News & Views section contains short articles summarizing recently published high-impact research in a way accessible to the broader public. The authors of the News & Views articles are selected by the editor among those reviewers of the corresponding research articles that left the best impression during the review process.

1. Neelakandan Marath Santhosh, Kush K. Updhyay, Petra Stražar, Gregor Filipič, Janez Zavašnik, André Mão de Ferro, Rui Pedro Silva, Elena Tatarova, Maria de Fátima Montemor, Uroš Cvelbar, “Advanced carbonnickel sulfide hybrid nanostructures: extending the limits of batterytype electrodes for redox-based supercapacitor applications”, ACS applied materials & interfaces, 2021, 13, 17, 20559–20572.

2. Juan Casanova-Chafer, Polona Umek, Selene Acosta, Carla Bittencourt, Eduard Llobet, “Graphene loading with polypyrrole nanoparticles for trace-level detection of ammonia at room temperature”, ACS applied materials & interfaces, 2021, 13, 34, 40909–40921.

3. Petra Draksler, Urška Mikac, Peter Laggner, Amrit Paudel, Biljana Janković, “Polyethylene oxide matrix tablet swelling evolution: the impact of molecular weight and tablet composition”, Acta pharmaceutica, 2021, 71, 2, 215-243.

4. Andraž Bradeško, Lovro Fulanović, Marko Vrabelj, Aleksander Matavž, Mojca Otoničar, Jurij Koruza, Barbara Malič, Tadej Rojac, “Multifunctional cantilevers as working elements in solid-state cooling devices”, Actuators, 2021, 10, 3, 58.

5. Gregor Pirnat, Matjaž Humar, “Whispering gallery-mode microdroplet tensiometry”, Advanced photonics research, 2021, 2, 11, 2100129.

6. Lukas Link, Manisha Pathak, Franziska Jach, Primož Koželj, Alim H. Ormeci, Peter Höhn, Rainer Niewa, “The reduced nitridogermanates(III) Ca6[Ge2N6] and Sr6[Ge2N6] with Ge-Ge bonds”, Angewandte Chemie, 2021, 60, 14, 7691-7696.

7. Franziska Jach et al. (12 authors), “Tricyanidoferrates(-IV) and ruthenates(-IV) with non-innocent cyanido ligands”, Angewandte Chemie, 2021, 60, 29, 15879-15885.… Read the rest “Original articles – 2021”