In the lecture series "Science with Impact" we want to specifically address the question of how research can have an impact and benefit society in post-factual times. Throughout the year, speakers from BAM and from our worldwide network will highlight current issues in our five thematic areas of energy, infrastructure, environment, materials and analytical sciences.

The series started with a digital symposium on "Trust in Future Technologies" in March.

You can find the previous lectures here.

Current dates of the lecture series "Science with Impact":

Lecture on 27.08.2021

Prof. Dr. Claudia Felser
Director and Scientific Member at the Max Planck Institute for Chemical Physics of Solids, Dresden

Invitation
DateFriday, 27 August 2021, 02:00 pm
Type of EventHybrid
TopicTopology and Chirality
PresenterProf. Dr. Claudia Felser
Director and Scientific Member at the Max Planck Institute for Chemical Physics of Solids, Dresden
Summary

Topology, a mathematical concept, recently became a hot and truly transdisciplinary topic in condensed matter physics, solid state chemistry and materials science. All 200 000 inorganic materials were recently classified into trivial and topological materials: topological insulators, Dirac, Weyl and nodal-line semimetals, and topological metals [1]. The direct connection between real space: atoms, valence electrons, bonds and orbitals, and reciprocal space: bands and Fermi surfaces allows for a simple classification of topological materials in a single particle picture. More than 25% of all inorganic compounds host topological bands, which opens also an infinitive play-ground for chemistry [1,2]. Beyond Weyl and Dirac, new fermions can be identified in compounds that have linear and quadratic 3-, 6- and 8- band crossings that are stabilized by space group symmetries [3]. Crystals of chiral topological materials CoSi, AlPt and RhSi were investigated by angle resolved photoemission and show giant unusual helicoid Fermi arcs with topological charges (Chern numbers) of ±2 [4]. In agreement with the chiral crystal structure two different chiral surface states are observed. A quantized circular photogalvanic effect is theoretically possible in Weyl semimetals. However, in the multifold fermions with opposite chiralities where Weyl points can stay at different energies, a net topological charge can be generated. [5]. However, chirality is also of interest for chemists [6], especially because of the excellent catalytic performance of the new chiral Fermions AlPt and PdGa [7]. The open question is the interplay between Berry curvature, chirality, orbital moment and surface states.

1. Bradlyn et al., Nature 547 298, (2017), Vergniory, et al., Nature 566 480 (2019), Xu et al. Nature 586 (2020) 702.
2. Nitesh Kumar, Satya N. Guin, Kaustuv Manna, Chandra Shekhar, and Claudia Felser, doi.org/10.1021/acs.chemrev.0c00732
3. Bradlyn, et al., Science 353, aaf5037A (2016)
4. Sanchez et al., Nature 567 (2019) 500, Schröter et al., Nature Physics 15 (2019) 759, Schröter Science 369 (2020) 179, Sessi et al, Nature Communications 11 (2020) 3507, Yao et al., Nature Communications 11 (2020) 2033
5. Dylan Rees, et al., Science Advances 6 (2020) eaba0509, Congcong Le, Yang Zhang, Claudia Felser, Yan Sun, Physical Review B 102 (2020) 121111(R), Zhuoliang Ni, et al., npj Quantum Materials volume 5 (2020) 96, Zhuoliang Ni, et al.,, Nature Communications 12 (2021) 154
6. B. Yan, et al., Nature Com. 6 (2015) 10167, Guowei Li and Claudia Felser, APL 116 (2020) 070501.
7. Qun Yang, et al., Advanced Materials 32 (2020) 1908518, Guowei Li, to be published

LanguageEnglish
Link-RegistrationWebex
BAM Contact Dr. Franziska Emmerling, franziska.emmerling[at]bam.de

Lecture on 30.09.2021

Prof. Dierk Raabe
Max-Planck Institut für Eisenforschung

Invitation
DateThursday, 30 September 2021, 02:00 pm
Type of EventWebinar
TopicThe Materials Science of Sustainable Metals and a Circular Economy
PresenterProf. Dierk Raabe
Max-Planck Institut für Eisenforschung
SummaryFor more than five millennia metallic alloys have been serving as the backbone of civilization. Today >2 billion tons of metals are produced every year. The demand for some materials such as steels, aluminum and copper is expected to double or even triple by 2050. Metals require a lot of energy for their extraction, synthesis and downstream manufacturing, qualifying them as the largest single industrial source of greenhouse gas emissions and energy consumption. The success of metals thus brings them into a position where they must play an important role in addressing the associated environmental challenges and the coming of a partially circular economy. The presentation discusses pathways for improving the direct sustainability of structural metals, in areas including reduced-carbon-dioxide primary production, recycling, scrap-compatible alloy design, contaminant-tolerance of alloys and improved alloy longevity. The lecture also discusses the effectiveness and technological readiness of individual measures, and also shows how novel structural materials enable improved energy efficiency.
LanguageEnglish
Link-RegistrationWebex
BAM Contact Prof. Dr. Robert Maaß, robert.maass[at]bam.de