Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A 50-year quest to isolate the thermoelectric effect is now over: Magnon drag unveiled

19.12.2011
As electrons move past atoms in a solid, their charge distorts the nearby lattice and can create a wave.

Reciprocally, a wave in the lattice affects the electrons motion, in analogy to a wave in the sea that pushes a surfer riding it. This interaction results in a thermoelectric effect that was first observed during the 1950´s and has come to be known as phonon-drag, because it can be quantified from the flow of lattice-wave quanta (phonons) that occurs over the temperature gradient.

Soon after the discovery of the phonon drag, an analogous phenomenon was predicted to appear in magnetic materials: the so called magnon drag. In a magnetic material the intrinsic magnetic moment or spin of the electrons arrange in an organized fashion. In ferromagnets, the spins maintain a parallel orientation. If a distortion in the preferred spin orientation occurs, a spin wave is created that could affect electron motion. It is therefore reasonable to expect that the flow of magnons (spin-wave quanta) could also drag the electrons.

Despite the similarities with phonon drag, the observation of the magnon drag has been elusive, and only a few indirect indications of its existence have been reported over the years. The main reason being the presence of other thermoelectric effects, most notably the phonon drag, that make it difficult to discriminate its contribution to the thermopower.

Researchers of ICN´s Physics and Engineering of Nanodevices Group, Marius V. Costache, Germán Bridoux, Ingmar Neumann and group leader ICREA Prof. Sergio O. Valenzuela used a unique device geometry to discriminate the magnon drag from other thermoelectric effects. The device resembles a thermopile formed by a large number of pairs of ferromagnetic wires placed between a hot and a cold source and connected thermally in parallel and electrically in series. By controlling the relative orientation of the magnetization in pairs of wires, the magnon drag can be studied independently of the electron and phonon drag thermoelectric effects.

The work is very timely as thermoelectric effects in spin-electronics (spintronics) are gathering increasing attention as a means of managing heat in nanoscale structures and of controlling spin information by using heat flow. Measurements as a function of temperature reveal the effect on magnon drag following a variation of magnon and phonon populations.

This information is crucial to understand the physics of thermal spin transport. It both provides invaluable opportunities to gather knowledge about electron-magnon interactions and may be beneficial for energy conversion applications and for the search of novel pathways towards transporting spin information.

Prof. Dr. Sergio O. Valenzuela | EurekAlert!
Further information:
http://www.icn.cat

More articles from Physics and Astronomy:

nachricht Scientists propose synestia, a new type of planetary object
23.05.2017 | University of California - Davis

nachricht Turmoil in sluggish electrons’ existence
23.05.2017 | Max-Planck-Institut für Quantenoptik

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

 
Latest News

Scientists propose synestia, a new type of planetary object

23.05.2017 | Physics and Astronomy

Zap! Graphene is bad news for bacteria

23.05.2017 | Life Sciences

Medical gamma-ray camera is now palm-sized

23.05.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>