A new technology allows the magnetic cooling of chips based on the straining of materials. The research, conducted by Luis Hueso, a researcher at CIC nanoGUNE, and researchers from the University of Cambridge, among others, was recently published in the journal Nature Materials.
Current cooling systems, be they refrigerators, freezers or air-conditioning units, make use of the compression and expansion of a gas. When the gas is compressed, it changes into a liquid state; when it expands, it evaporates once again. To evaporate, it needs heat, which it extracts from the medium it touches. This extraction of heat cools the medium significantly, and by extension, anything placed in the medium. However, compressor-based systems using this cooling method are not always effective and can be harmful to the environment.
The researchers explored an alternative ― magnetic cooling ― which uses a magnetic material instead of a gas, and magnetizing and demagnetizing cycles instead of compression-expansion cycles. Magnetic cooling is a technique based on the magnetocaloric effect; in other words, it is based on the properties displayed by certain materials to modify their temperature when a magnetic field is applied to them.
Application of a magnetic field leads to many problems in current miniaturized technological devices such as electronic chips and computer memories. Because the magnetic field can interact negatively, owing to its effect on nearby units, any cooling effort to harness the magnetocaloric effect must demonstrate a way to control the magnetization of the adjacent circuits.
As reported in Nature Materials, researchers from nanoGUNE have discovered that by using the straining of materials, they can get around the problems of applying a magnetic field.
"By straining the material and then relaxing it, an effect similar to that of a magnetic field is created, thus inducing the magnetocaloric effect responsible for cooling," explains Hueso. The new technology has allowed researchers to have a more local and controlled cooling method that does not interfere with other parts of a device.
Films, just 20 nm in size, and consisting of lanthanum, calcium, manganese and oxygen have been developed with the aim of finding materials that are efficient, economical and environmentally friendly.
The research is being driven by the fact that most of the money spent on data center servers goes to cooling. The researchers believe the new technology could be effective in applications of this kind.