Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Indications of the origin of the Spin Seebeck effect discovered

07.09.2015

Thermally excited magnetic waves enable generation of electricity using insulators

The recovery of waste heat in all kinds of processes poses one of the main challenges of our time to making established processes more energy-efficient and thus more environmentally friendly. The Spin Seebeck effect (SSE) is a novel, only rudimentarily understood effect, which allows for the conversion of a heat flux into electrical energy, even in electrically non-conducting materials.

A team of physicists at Johannes Gutenberg University Mainz (JGU), the University of Konstanz, the University of Kaiserslautern, and the Massachusetts Institute of Technology (MIT) have now succeeded in identifying the origin of the Spin Seebeck effect. By the specific investigation of the material- and temperature-dependence of the effect, the German and American researchers were able to show that it exhibits a characteristic length scale attributable to its magnetic origin.

This finding now allows for the advancement of this long-time controversial effect in terms of first applications. The resulting research paper was published in the scientific journal Physical Review Letters, with a fellow of the JGU-based Graduate School of Excellence "Materials Science in Mainz" (MAINZ) as first author.

The Spin Seebeck effect represents a so-called spin-thermoelectric effect, which enables the conversion of thermal energy into electrical energy. Contrary to conventional thermoelectric effects it also enables the recovery of heat energy in magnetic insulators in combination with a thin metallic layer.

Owing to this characteristic, it was assumed that the effect originates from thermally excited magnetic waves. The currently employed method of measurement, which makes use of a second metallic layer converting these magnetic waves into a measurable electrical signal, has so far not been able to allow for a distinct assignment of experimentally detected signals.

By measuring the effect for different material thicknesses in the range of a few nanometers up to several micrometers as well as for different temperatures, the scientists have found characteristic behavior. In thin films the signal amplitude increases with increasing material thickness and eventually saturates after exceeding a sufficient thickness.

In combination with the detected enhancement of this critical thickness at low temperatures, the agreement with the theoretical model of thermally excited magnetic waves developed at Konstanz could be demonstrated. With these results, the researchers were able for the first time to reveal a direct relation between the assumed thermally excited magnetic waves and the effect.

"This result provides us with an important building block of the puzzle of the comprehension of this new, complex effect, unambiguously demonstrating its existence," said Andreas Kehlberger, Ph.D. student at Johannes Gutenberg University Mainz and first author of the publication.

"I am very pleased that this exciting result emerged in a cooperation of a doctoral candidate out of my group at the Graduate School of Excellence 'Materials Science in Mainz' together with co-workers from Kaiserslautern and our colleagues from Konstanz, with whom we collaborate within the Priority Program 'Spin Caloric Transport' funded by the German Research Foundation (DFG)," emphasized Professor Mathias Kläui, director of the MAINZ Graduate School of Excellence based at Mainz University.

"It shows that complex research is only possible in teams, for instance with funding by the German Federal Ministry of Education and Research (BMBF) through the Mainz-MIT Seed Fund."

The MAINZ Graduate School of Excellence was originally approved as part of the Federal and State Excellence Initiative in 2007 and received a five-year funding extension in the second round in 2012 – a tremendous boost for the Mainz-based materials scientists and for the sponsorship of young researchers at JGU.

The MAINZ Graduate School consists of work groups at Johannes Gutenberg University Mainz, the University of Kaiserslautern, and the Max Planck Institute for Polymer Research in Mainz. One of its focal research areas is spintronics, where cooperation with leading international partners plays an important role.

Publication:
Kehlberger, A. et al.
Length Scale of the Spin Seebeck Effect
Physical Review Letters, 28 August 2015
DOI: 10.1103/PhysRevLett.115.096602
http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.115.096602

Further information:
Professor Mathias Kläui
Condensed Matter Theory Group
Institute of Physics
Johannes Gutenberg University Mainz
55099 Mainz, GERMANY
phone +49 6131 39-23633
e-mail: klaeui@uni-mainz.de
http://www.klaeui-lab.physik.uni-mainz.de/
http://www.mainz.uni-mainz.de/ (MAINZ Graduate School of Excellence)

Weitere Informationen:

http://www.uni-mainz.de/presse/19572_ENG_HTML.php - press release
http://www.iph.uni-mainz.de/index_ENG.php - Institute of Physics at JGU
http://www.klaeui-lab.physik.uni-mainz.de/index.php - Kläui Lab at JGU
http://www.mainz.uni-mainz.de/ - MAINZ Graduate School of Excellence

Petra Giegerich | idw - Informationsdienst Wissenschaft

More articles from Materials Sciences:

nachricht Metallic nanoparticles will help to determine the percentage of volatile compounds
20.10.2017 | Lomonosov Moscow State University

nachricht New material for digital memories of the future
19.10.2017 | Linköping University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

Metallic nanoparticles will help to determine the percentage of volatile compounds

20.10.2017 | Materials Sciences

Shallow soils promote savannas in South America

20.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>