Thermoelectric effects in magnetic nanostructures

PhD ceremony: Mr. F.L. Bakker, 14.30 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Thermoelectric effects in magnetic nanostructures

Promotor(s): prof. B.J. van Wees

Faculty: Mathematics and Natural Sciences

Electron transport is one of the most important physical phenomena used in todays technology. All modern electrical equipment, ranging from vacuum cleaners till high-end microprocessors is essentially founded on this type of transport. However, in most cases the electron's full potential is not used and most applications only exploit the negative elementary charge that it possesses. The energy and the magnetic moment of the electrons are properties which are used in thermoelectricity and spin-electronics (spintronics), respectively. Spintronics focuses on the transfer of magnetic moments for the information transport, while thermoelectric phenomena (e.g. the Peltier and Seebeck effect) have found their application in devices for electric heating/cooling or thermocouples. This thesis describes the fundamental interactions between the three types of transport (charge, heat, spin) in magnetic nanostructures. The experimental work described here is part of a wider research direction, called spin-caloritronics. This research branch of spintronics studies the role of magnetic moments in heat transport. The potential advantages of spin-caloritronic effects with respect to regular thermoelectricity can be found in the easy manipulation of magnetic textures at the nanoscale. This enables very localized and programmable control of heat flow which might prove useful for thermopower energy harvesting or refrigeration. However, the previously discussed effects are weak and far from direct applications. Nonetheless, a combination of new developments in this field and by exploring novel materials it could one day lead to the implementation of spin-caloritronics in our everyday electronic devices.