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Posted: Jul 26, 2011

Give waste heat inside microprocessors new directions

(Nanowerk News) Spin caloritronics describes a new area of research: What happens if you heat a magnet? Usually if a material is heated, the temperature difference leads to electrical voltage, which is known as thermoelectric voltage or Seebeck effect. Electric components including magnetic elements – those are made of two thin magnetic layers, which are separated by a thin oxide layer with only a few atoms – are for example used for hard drives as read head. The use of those magnetic tube elements as a non-volatile memory cell in processors, which allows information to be preserved without electricity supply, is currently part of research.
An international research team including scientists from University Goettingen, Bielefeld and Giessen as well as from Massachusetts Institute of Technology (MIT) in the USA has previously developed a method that enables us to affect the thermoelectric voltage of electrons inside the tube systematic by a modification of magnetization. This is a way to control the conversion of heat into electric power.
These results could contribute to the development of new economical microprocessors. They have been published in the online version of Nature Materials ("Seebeck effect in magnetic tunnel junctions").
Elementary particles, many atomic nuclei and atoms with specific electron configuration have a so called spin, which describes the rotation around its own axis. This makes alternative, spin based ways of electronic data processing possible, called spin electronics. With melting the areas spin electronic and conversion of energy inside innovative materials new effects emerge. Recently a Japanese research team could demonstrate that thermal injection of spin through tube barriers into the semiconductor silicium is possible.
The team around Prof. Dr. Markus Münzenberg has now heated tube elements with laser pulse and discovered a new effect: The spin transport through the thin oxide layer (tube barrier) leads directly to thermal voltage. This voltage could be reduced and increased by changing the magnetization. With that they could affect the whole tube element's thermal voltage. The scientists say that a change up to 1000 percent will be possible. This newly developed effect of switching thermal voltage in magnetic tube elements was named Magneto-Seebeck effect.
"With that it is possible to regulate the local conversion of energy inside smallest elements. In the future we will be able to systematically give so far unused energy in microprocessors back into the computer system" says Prof. Münzenberg. He is head of a research team at University Goettingen's I. Physical Institute. The joint research of those three German universities is funded with more than one million euro since July 2011 within the framework of the new focus program "Spin Caloric Transport (SpinCat) – SPP 1538" of the DFG (Deutsche Forschungsgemeinschaft).
Source: Kompetenznetze Deutschland
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