Waste heat from computers and electronics circuits creates a lot of problems including more power consumption, component failures, frequent shutdowns, early wearout of components, maintenance cost for cooling and thermal management systems. Researchers have been studying the ways to utilize waste heat by converting into electric power or other means of energy harvesting. But still most of the energy harvesting methods are not practically applicable to computers and portable electronics, because of their size, cost, and efficiency. Low temperature heat contains very little capacity to do work, so the heat is qualified as waste heat and rejected to the environment.

The disposal of waste heat from microchips and other electronic components, represents a significant engineering challenge. This necessitates the use of cooling fans, heatsinks, etc. to dispose of the heat. Especially computer processors release a lot of waste heat that affects the performance of computers.

Now researchers found a new way of waste heat energy harvesting, using Magnetic Nanoswitches by generating Thermoelectric Voltages. Thanks to a recently discovered effect in magnetic tunnel structures, where thermoelectric voltages in nano-electronic junctions can be controlled. The heat which occurs in tiny computer processors might soon be no longer useless. It could be used to switch these processors more easily or to store data more efficiently! These are two of the several potential applications made possible by a discovery made at the Physikalisch-Technische Bundesanstalt (PTB). This so-called “thermoelectric voltage” may well be very interesting — mainly for the use of nano-junctions, i.e. small components based on magnetic tunnel structures.

Magnetic Nanoswitch for Thermoelectric Voltages

Magnetic Nanoswitch for Thermoelectric VoltagesMagnetic tunnel structures consist of two magnetic layers separated only by a thin insulation layer of approx. 1 nm – the so-called “tunnel barrier”. The magnetic orientation of the two layers inside the tunnel structure has a great influence on its electrical properties: if the magnetic moments of the two layers are parallel to each other, the resistance is low; if, on the contrary, they are opposed to each other, the resistance is high. The change in the resistance when switching the magnetisation can amount to more than 100 %. It is therefore possible to control the electric current flowing through the magnetic tunnel structure efficiently by simply switching the magnetisation.

Applications of Magnetic Tunnel Structures

Today, magnetic tunnel structures already occur in various areas of information technology. They are used, for example, as magnetic storage cells in non-volatile magnetic memory chips (the so-called “MRAMs” – Magnetic Random Access Memories) or as highly sensitive magnetic sensors to read out the data stored on hard disks. In the future, The new effect discovered at PTB will add new applications to the existing ones: monitoring and controlling thermoelectric voltages and currents in highly integrated electronic circuits. In future, this new effect could be applied, for example, by using and converting the energy of waste heat occurring in integrated circuits in a targeted way.