Highlights

  • Researchers identify 13 monolayers as potentially promising quantum spin Hall insulator candidates

    In a recently published paper, Relative Abundance of Z2 Topological Order in Exfoliable Two-Dimensional Insulators, researchers from MARVEL director Nicola Marzari’s Laboratory of theory and simulation of materials (THEOS) screened a comprehensive database and identified 13 monolayers that are dynamically stable and potentially exfoliable quantum spin Hall insulators. This highlights a relative abundance of such topological order of around 1%. The paper was published in Nano Letters.

  • MARVEL researchers, partners present work on materials for energy at Materials Science Day

    NCCR MARVEL and CCMX, the Competence Centre for Materials Science and Technology, hosted their third annual Materials Science Day on October 8 to present both experimental and modeling approaches to the development of innovative new materials. The event, meant to highlight cutting-edge research and give people a chance to network, drew more than 60 people from industry and academia.

  • MARVEL Sector Days give industry a chance to help shape research

    Research should be driven by societal issues—we need to pursue what is urgent and needed for the community at large. Just as the NCCR MARVEL seeks the guidance and expertise of a scientific advisory board in developing lines of research, we also seek insight from industry. 

  • Machine learning approach predicts electron densities with DFT accuracy

    Clémence Corminboeuf, Michele Ceriotti and colleagues at EPFL have developed a machine learning model that can predict the electron density from atomic coordinates. The approach may facilitate the characterization of non-covalent interactions, helping researchers  understand complex interactions between biomolecules and potentially assist in the design of self-assembled materials and drugs. The research was recently published in the journal Chemical Science.

  • Science paper proposes non-Abelian band topology

    A paper published in the journal Science by NCCR MARVEL's QuanSheng Wu, postdoc in the group of Oleg Yazyev at EPFL, Alexey Soluyanov, professor at the Physics Institute of the University of Zurich as well as group leader in Design & Discovery Project 6, and colleague Tomáš Bzdušek at Stanford University  introduces non-Abelian topological charges that characterize line nodes inside the momentum space of certain symmetric crystalline metals with weak spin-orbit coupling. The analysis goes beyond the standard approach to band topology, and implies the existence of 1D topological phases not present in existing classifications.

  • Hybrid functional molecular dynamics give unprecedented view on the nature of the wet electron

    The hydrated electron has been widely studied, but the atomistic mechanism leading to its formation and the nature of the precursor states remain poorly understood. One of those states, the wet electron, has been used to explain certain spectroscopic observations, but its binding energy and atomic structure have been difficult to characterize. Now, using hybrid functional molecular dynamics simulations, NCCR MARVEL researchers have unveiled the ultrafast solvation mechanism that leads to the hydrated electron. The picture gives an unprecedented view of the nature of the wet electron, instrumental to understanding the properties of this fundamental species in liquid water. The research has been published in Chemical Science.

  • MARVEL researchers investigate how MOF structures affect dieletric properties

    The modern microelectronics industry has a huge need for highly efficient electric insulators. Structures built around the medium with the lowest possible dielectric constant, that is, a vacuum, or air, may be their best bet. Metal-organic frameworks (MOFs) feature, among other advantages, large pores and poorly correlated scaffolding and so may serve this purpose well. Despite the huge potential, few studies have pursued either systematic experimental measurements or simulations to estimate the dielectric constant of MOFs. This lack of data makes it difficult to link properties and performance and hinders the design of an optimal structure–property correlation. NCCR MARVEL researchers looked to fill this gap in knowledge with a study into how the atomic and electronic structures of MOFs affect their dieletric properties. The results of their work were recently published in the Journal of the American Chemical Society. 

  • MARVEL researchers introduce a novel heat transport theory in quest for more efficient thermoelectrics

    MARVEL researchers have developed a novel microscopic theory that is able to describe heat transport in very general ways, and applies equally well to ordered or disordered materials such as crystals or glasses and to anything in between. This is not only a significant first—no transport equation has been able so far to account simultaneously for these two regimes—it also shows, surprisingly, that heat can tunnel, quantum-mechanically, rather than diffuse away, like an atomic vibration. The new equation will also allow the accurate prediction of the performance of thermoelectric materials for the first time. With ultralow, glass-like, thermal conductivity, such materials are one of the holy grails of energy research: they can turn heat into electricity or use electricity for cooling without needing to resort to pumps and environmentally harmful gases. The article was published in Nature Physics.

  • Strain modifies the valley structure of 2D materials, leads to remarkable improvements in conductivity

    NCCR MARVEL researchers have investigated strain as a means of engineering the valley structure of 2D materials. They found that it leads to remarkable improvements in conductivity—in the example of arsenene, they showed the enhancement factor to be on the order of 600%—by suppressing intervalley scattering and thus enhancing electron mobility. The approach could be used to design or discover 2D materials that combine both good carrier mobility and the energy gap needed for use in logical devices. The research has been published in Nano Letters. 

  • New study gives compelling evidence that tungsten diphosphide is a type-II Weyl semimetal

    Researchers at NCCR MARVEL have combined first principles calculations with soft X-ray angle-resolved photoemission spectroscopy to examine tungsten diphosphide’s electronic structure, characterizing its Weyl nodes for the very first time. In agreement with density functional theory calculations, the results revealed two pairs of Weyl nodes lying at different binding energies. The observation of the Weyl nodes, as well as the tilted cone-like dispersions in the vicinity of the nodal points, provides compelling evidence that the material is a robust type-II Weyl semimetal with broken Lorentz invariance. This is as MARVEL researchers predicted two years ago. The research has been published in Physical Review Letters as an Editor's Suggestion.

  • New biologically derived metal-organic framework mimics DNA

    EPFL chemical engineers led by Kyriakos Stylianou, experimental group leader in MARVEL Design and Discovery Project 4, have synthesized a biologically-derived metal-organic framework on which the hydrogen bonding that forms the DNA double helix can be mimicked and studied like never before. The paper, Nucleobase pairing and photodimerization in a biologically derived metal-organic framework nanoreactor, has been published in Nature Communications.

  • Researchers discover self-healing catalyst for potential large-scale use in safe hydrogen production and storage

    Researchers working within NCCR MARVEL have discovered a self-healing catalyst that can be used to release hydrogen through the hydrolytic dehydrogenation of ammonia borane. The catalyst, SION-X, is based on the abundant mineral Jacquesdietrichite, is sustainable, air stable and can be easily regenerated, stored and handled. These characteristics mean that it may offer significant advantages over existing catalysts used in the production of the clean and renewable energy carrier hydrogen. The research has been published in the Journal of Materials Chemistry A.