Non-Abelian topological charge explains why certain Weyl points with different chirality do not annihilate upon collision

Common wisdom holds that two Weyl points with different chirality will annihilate when they collide with each other. Now, combining theoretical arguments with first-principles calculations, researchers including Oleg Yazyev, Chair of Computational Condensed Matter physics at EPFL and scientist  QuanSheng Wu have predicted, on the contrary, that this is not the case in Weyl points (WP) occurring near the Fermi level of zirconium telluride. In the paper Non-Abelian reciprocal braiding of Weyl points and its manifestation in ZrTe, recently published in Nature Physics, they report their finding that a pair of Weyl points in the C2T invariant plane around the K point carry non-trivial values of the non-Abelian charge, the Euler number, and will not annihilate, but rather convert into a nodal line (NL) in the mirror invariant plane when applying uni-axial strain along the [001] direction.

MARVEL research highlighted in JCP special issue on machine learning in chemical physics

Edited by NCCR MARVEL group leaders Michele Ceriotti and Anatole von Lilienfeld as well as colleague Cecilia Clementi of Rice University, the JCP Special Topic on “Machine Learning Meets Chemical Physics” features papers from the labs of Clemence Corminboeuf and Ceriotti at EPFL and von Lilienfeld at the University of Basel. The issue focuses on research that puts an emphasis on the interplay between machine learning and chemical physics, whether by incorporating physical principles and chemical intuition into model construction or by using machine learning to recognize new laws or general design principles. In the article below, we look at highlights of the research contributed from the three MARVEL labs. 

2-D materials for ultrascaled field-effect transistors: One hundred candidates under the ab initio microscope

Researchers led by Mathieu Luisier from the Institute for Integrated Systems (IIS) at ETH Zurich and NCCR MARVEL's Director Nicola Marzari at EPFL have set out to develop a comprehensive atlas of 2-D materials that might be capable of challenging currently  manufactured silicon-based transistors, so-called Si FinFETs. The new simulations are based on earlier results from Marzari and his team, who used complex simulations on the Swiss National Supercomuting Centre's supercomputer "Piz Daint" to sift through a pool of more than 100,000 materials to identify 1,825 from which it might be possible to obtain 2-D layers of material. The paper 2‑D Materials for Ultrascaled Field-Effect Transistors: One Hundred Candidates under the Ab Initio Microscope, recently published in the journal ACS Nano, identifies 13 particularly promising candidates. 

MARVEL groups join BIG-MAP consortium to accelerate battery research

A new European project with a budget of about 20 million euros, led by the Technical University of Denmark (DTU) is aiming to develop the next generation of super batteries.

MARVEL Junior Seminar — July 2020

The MARVEL Junior Seminar series will not be taking any summer break, and we are continuing in videoconferencing mode. We are therefore pleased to propose the 34th MARVEL Junior Seminar: Michele Invernizzi (ETHZ/USI) and Giuliana Materzanini (EPFL) will present their research. The seminar will be chaired by Kristians Cernevics.

MARVEL Junior Seminar — August 2020

The MARVEL Junior Seminar series is continuing in videoconferencing mode (and we'll hopefully be back soon with pizza and cakes!). We are therefore pleased to propose the 35th MARVEL Junior Seminar: Kristjan Eimre (Empa) and Anders  Christensen (UniBas) will present their research. The seminar will be chaired by Max Veit.