From The MPG Institute for Chemical Physics of Solids [MPG institut für Chemische Physik fester Stoffe] (DE) via The MPG Institute for the Advancement of Science [MPG zur Förderung der Wissenschaften e. V ](DE): “A new way to generate electricity from waste heat-using an antiferromagnet for solid devices”

1

From The MPG Institute for Chemical Physics of Solids [MPG institut für Chemische Physik fester Stoffe] (DE)

via

The MPG Institute for the Advancement of Science [MPG zur Förderung der Wissenschaften e. V ](DE) is a research institute of the Max Planck Society. Located in Dresden, the institute primarily conducts basic research in the natural sciences in the fields of physics and chemistry.

11.23.21

Prof. Dr. Claudia Felser
Director
+49 351 4646-3000
Claudia.Felser@cpfs.mpg.de

Yu Pan
Group Leader
+49 351 4646-3424
Yu.Pan@cpfs.mpg.de

Media Contact
Ingrid Rothe
+49 351 4646-3001
PR@cpfs.mpg.de

Researchers at the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany, together with collaborators at The Ohio State University (US) and The University of Cincinnati (US), have discovered, for the first time, a giant thermoelectric effect in an antiferromagnet. The study published in Nature Materials in a paper entitled Giant anomalous Nernst signal in the antiferromagnet YbMnBi2 shows, surprisingly, that antiferromagnets can have the same value of the anomalous Nernst effect as conventional ferromagnets, but without any stray magnetic fields that would otherwise affect surrounding devices. The newly discovered recipe for generating large Nernst voltages opens a new research direction for the development of highly efficient thermoelectric devices.

Forcing electrons to flow perpendicularly to a heat flow requires an external magnetic field – this is known as the Nernst effect. In a permanently magnetized material (a ferromagnet) an anomalous Nernst effect (ANE) exists that can generate electricity from heat even without a magnetic field. The anomalous Nernst effect scales with the magnetic moment of the ferromagnet. An antiferromagnet, with two compensating magnetic sublattices shows no external magnetic moment and no measurable external magnetic field and therefore should not exhibit any ANE. However, we have recently understood that by the new concept of topology can be applied to achieve large Nernst effects in magnets. In particular, we have learned that the quantity known as the Berry phase is related to the ANE and can greatly increase it. However, the ANE in antiferromagnets is still largely unexplored, in part because the ANE was not thought to exist. Remarkably, a joint research team from the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany, together with collaborators at the Ohio State University and the University of Cincinnati, has found a large anomalous Nernst effect, larger than is known in almost all ferromagnets in YbMnBi2, an antiferromagnet.

The ANE that has been observed is likely a result of topology, the high spin-orbit coupling, and the complex and not fully compensated magnetic structure of YbMnBi2. The canted spin structure in YbMnBi2 breaks time reversal symmetry and provides a non-zero Berry curvature. At the same time, the large spin-orbit coupling of the heavy bismuth element helps to produce a large extrinsic contribution. Based on this recipe, a certain class of antiferromagnets with a non-collinear spin structure and with large spin-orbit coupling can exhibit a large anomalous Nernst effect. The researchers were surprised when they observed such a large ANE in YbMnBi2, reaching 6 µV/K, which is a record value for antiferromagnets and as high as those values previously observed for the best ferromagnets.

1
Schematics of thermoelectric devices based on the Seebeck effect (a) and Nernst effect (b). The Nernst device needs only one material and eliminates the complex electrical connections required in the Seebeck device, especially at the hot side. B, magnetic field; E, electrical field; ∇T, temperature gradient. Credit: MPI CPfS.

“Although the ANE value is surprisingly large and the zT value is much higher than that of ferromagnets, the overall thermoelectric performance still needs to be improved for practical applications,” says Yu Pan, group leader in the department of Solid State Chemistry at the MPI CPfS in Dresden. She continues, “Nevertheless, this study shows the great potential of antiferromagnets for thermoelectric applications, as they have much better performance than ferromagnets. We believe our work is just the beginning of the discovery of even more interesting thermoelectric materials in the future.”

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The MPG Institute for the Advancement of Science [MPG zur Förderung der Wissenschaften e. V](DE) is Germany’s most successful research organization. Since its establishment in 1948, no fewer than 18 Nobel laureates have emerged from the ranks of its scientists, putting it on a par with the best and most prestigious research institutions worldwide. The more than 15,000 publications each year in internationally renowned scientific journals are proof of the outstanding research work conducted at MPG Institutes – and many of those articles are among the most-cited publications in the relevant field.

What is the basis of this success? The scientific attractiveness of the MPG Society is based on its understanding of research: MPG institutes are built up solely around the world’s leading researchers. They themselves define their research subjects and are given the best working conditions, as well as free reign in selecting their staff. This is the core of the Harnack principle, which dates back to Adolph von Harnack, the first president of the Kaiser Wilhelm Society, which was established in 1911. This principle has been successfully applied for nearly one hundred years. The MPG Society continues the tradition of its predecessor institution with this structural principle of the person-centered research organization.

The currently 83 MPG Institutes and facilities conduct basic research in the service of the general public in the natural sciences, life sciences, social sciences, and the humanities. MPG Institutes focus on research fields that are particularly innovative, or that are especially demanding in terms of funding or time requirements. And their research spectrum is continually evolving: new institutes are established to find answers to seminal, forward-looking scientific questions, while others are closed when, for example, their research field has been widely established at universities. This continuous renewal preserves the scope the Max Planck Society needs to react quickly to pioneering scientific developments.

MPG Society for the Advancement of Science [MPG Gesellschaft zur Förderung der Wissenschaften e. V.] is a formally independent non-governmental and non-profit association of German research institutes founded in 1911 as the Kaiser Wilhelm Society and renamed the MPG Society in 1948 in honor of its former president, theoretical physicist Max Planck. The society is funded by the federal and state governments of Germany as well as other sources.

According to its primary goal, the MPG Society supports fundamental research in the natural, life and social sciences, the arts and humanities in its 83 (as of January 2014) MPG institutes. The society has a total staff of approximately 17,000 permanent employees, including 5,470 scientists, plus around 4,600 non-tenured scientists and guests. Society budget for 2015 was about €1.7 billion.

The MPG Institutes focus on excellence in research. The MPG Society has a world-leading reputation as a science and technology research organization, with 33 Nobel Prizes awarded to their scientists, and is generally regarded as the foremost basic research organization in Europe and the world. In 2013, the Nature Publishing Index placed the MPG institutes fifth worldwide in terms of research published in Nature journals (after Harvard University (US), Massachusetts Institute of Technology (US),
Stanford University (US)and the National Institutes of Health (US)). In terms of total research volume (unweighted by citations or impact), the MPG Society is only outranked by the Chinese Academy of Sciences [中国科学院] (CN), the Russian Academy of Sciences [Росси́йская акаде́мия нау́к](RU) and Harvard University. The Thomson Reuters-Science Watch website placed the Max Planck Society as the second leading research organization worldwide following Harvard University, in terms of the impact of the produced research over science fields.

[The blog owner wishes to editorialize: I do not think all of this boasting is warranted when the combined forces of the MPG Society are being weighed against individual universities and institutions. It is not the combined forces of the cited schools and institutions, that could make some sense. No, it is each separate institution standing on its own.]

The MPG Society and its predecessor Kaiser Wilhelm Society hosted several renowned scientists in their fields, including Otto Hahn, Werner Heisenberg, and Albert Einstein.

History

The organization was established in 1911 as the Kaiser Wilhelm Society, or Kaiser-Wilhelm-Gesellschaft (KWG), a non-governmental research organization named for the then German emperor. The KWG was one of the world’s leading research organizations; its board of directors included scientists like Walther Bothe, Peter Debye, Albert Einstein, and Fritz Haber. In 1946, Otto Hahn assumed the position of President of KWG, and in 1948, the society was renamed the MPG Society after its former President (1930–37) Max Planck, who died in 1947.

The MPG Society has a world-leading reputation as a science and technology research organization. In 2006, the Times Higher Education Supplement rankings of non-university research institutions (based on international peer review by academics) placed the MPG Society as No.1 in the world for science research, and No.3 in technology research (behind AT&T Corporation and the DOE’s Argonne National Laboratory (US).

The domain mpg.de attracted at least 1.7 million visitors annually by 2008 according to a Compete.com study.

MPG Institutes and research groups

The MPG Society consists of over 80 research institutes. In addition, the society funds a number of MPG Research Groups (MPRG) and International MPG Research Schools (IMPRS). The purpose of establishing independent research groups at various universities is to strengthen the required networking between universities and institutes of the MPG Society.

The research units are primarily located across Europe with a few in South Korea and the U.S. In 2007, the Society established its first non-European centre, with an institute on the Jupiter campus of Florida Atlantic University (US) focusing on neuroscience.

The MPG Institutes operate independently from, though in close cooperation with, the universities, and focus on innovative research which does not fit into the university structure due to their interdisciplinary or transdisciplinary nature or which require resources that cannot be met by the state universities.

Internally, MPG Institutes are organized into research departments headed by directors such that each MPG institute has several directors, a position roughly comparable to anything from full professor to department head at a university. Other core members include Junior and Senior Research Fellows.

In addition, there are several associated institutes:

International Max Planck Research Schools
Together with the Association of Universities and other Education Institutions in Germany, the MPG Society established numerous International Max Planck Research Schools (IMPRS) to promote junior scientists:

Cologne Graduate School of Ageing Research, Cologne
International Max Planck Research School for Intelligent Systems, at the MPG Institute for Intelligent Systems (DE) located in Tübingen and Stuttgart
International Max Planck Research School on Adapting Behavior in a Fundamentally Uncertain World (Uncertainty School), at the Max Planck Institutes for Economics, for Human Development, and/or Research on Collective Goods
International Max Planck Research School for Analysis, Design and Optimization in Chemical and Biochemical Process Engineering, Magdeburg
International Max Planck Research School for Astronomy and Cosmic Physics, Heidelberg at the MPG for Astronomy
International Max Planck Research School for Astrophysics, Garching at the MPG Institute for Astrophysics
International Max Planck Research School for Complex Surfaces in Material Sciences, Berlin
International Max Planck Research School for Computer Science, Saarbrücken
International Max Planck Research School for Earth System Modeling, Hamburg
International Max Planck Research School for Elementary Particle Physics, Munich, at the MPG Institute for Physics
International Max Planck Research School for Environmental, Cellular and Molecular Microbiology, Marburg at the MPG Institute for Terrestrial Microbiology
International Max Planck Research School for Evolutionary Biology, Plön at the Max Planck Institute for Evolutionary Biology
International Max Planck Research School “From Molecules to Organisms”, Tübingen at the MPG Institute for Developmental Biology
International Max Planck Research School for Global Biogeochemical Cycles, Jena at the Max Planck Institute for Biogeochemistry
International Max Planck Research School on Gravitational Wave Astronomy, Hannover and Potsdam MPG Institute for Gravitational Physics
International Max Planck Research School for Heart and Lung Research, Bad Nauheim at the MPG Institute for Heart and Lung Research
International Max Planck Research School for Infectious Diseases and Immunity, Berlin at the Max Planck Institute for Infection Biology
International Max Planck Research School for Language Sciences, Nijmegen
International Max Planck Research School for Neurosciences, Göttingen
International Max Planck Research School for Cognitive and Systems Neuroscience, Tübingen
International Max Planck Research School for Marine Microbiology (MarMic), joint program of the MPG Institute for Marine Microbiology in Bremen, the University of Bremen [Universität Bremen](DE), the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, and the Jacobs University Bremen [Jacobs Universität Bremen] (DE)
International Max Planck Research School for Maritime Affairs, Hamburg
International Max Planck Research School for Molecular and Cellular Biology, Freiburg
International Max Planck Research School for Molecular and Cellular Life Sciences, Munich
International Max Planck Research School for Molecular Biology, Göttingen
International Max Planck Research School for Molecular Cell Biology and Bioengineering, Dresden
International Max Planck Research School Molecular Biomedicine, program combined with the ‘Graduate Programm Cell Dynamics And Disease’ at the University of Münster (DE) and the MPG Institute for Molecular Biomedicine (DE)
International Max Planck Research School on Multiscale Bio-Systems, Potsdam
International Max Planck Research School for Organismal Biology, at the University of Konstanz [Universität Konstanz] (DE) and the MPG Institute for Ornithology (DE)
International Max Planck Research School on Reactive Structure Analysis for Chemical Reactions (IMPRS RECHARGE), Mülheim an der Ruhr, at the Max Planck Institute for Chemical Energy Conversion (DE)
International Max Planck Research School for Science and Technology of Nano-Systems, Halle at MPG Institute of Microstructure Physics (DE)
International Max Planck Research School for Solar System Science at the University of Göttingen – Georg-August-Universität Göttingen (DE) hosted by MPG Institute for Solar System Research [Max-Planck-Institut für Sonnensystemforschung] (DE)
International Max Planck Research School for Astronomy and Astrophysics, Bonn, at the MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie] (DE) (formerly the International Max Planck Research School for Radio and Infrared Astronomy)
International Max Planck Research School for the Social and Political Constitution of the Economy, Cologne
International Max Planck Research School for Surface and Interface Engineering in Advanced Materials, Düsseldorf at MPG Institute for Iron Research [MPG Institut für Eisenforschung] (DE)
International Max Planck Research School for Ultrafast Imaging and Structural Dynamics, Hamburg

2

The Max Planck Institute for Chemical Physics of Solids (MPI CPfS) (German: Max-Planck-Institut für Chemische Physik fester Stoffe) is a research institute of the Max Planck Society. Located in Dresden, the institute primarily conducts basic research in the natural sciences in the fields of physics and chemistry.