Magnetic entropy and cooling

    Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsResearch

    Abstract

    Some manifestations of magnetism are well-known and utilized on an everyday basis, e.g. using a refrigerator magnet for hanging that important note on the refrigerator door. Others are, so far, more exotic, such as cooling by making use of the magnetocaloric eect. This eect can cause a change in the temperature of a magnetic material when a magnetic eld is applied or removed. For many years, experimentalists have made use of dilute paramagnetic materials to achieve milliKelvin temperatures by use of the magnetocaloric eect. Also, research is done on materials, which might be used for hydrogen, helium or nitrogen liquefaction or for room-temperature cooling. The magnetocaloric eect can further be used to determine phase transition boundaries, if a change in the magnetic state occurs at the boundary.In this talk, I will introduce the magnetocaloric eect (MCE) and the two equations, which characterize the eect: the isothermal magnetic entropy change and the adiabatic temperature change. Some of the manifestations and utilizations of the MCE will be touched upon in a general way and nally I will talk about the results I have obtained on a sample of Gadolinium Iron Garnet (GdIG, Gd3Fe5O12), which is a rather complex magnetic system. GdIG has three magnetic sublattices, one Gd and two Fe. The Fe sites are strongly coupled antiferromagnetically, i.e. the magnetic moments are anti-parallel, while the Gd magnetic moment is weakly coupled antiferromagnetically to the resulting Fe moment. This results in a compensation temperature, where the total magnetic moment is zero and my study has focused on this temperature region.
    Original languageEnglish
    Title of host publicationProgram and abstracts
    PublisherDanish Physical Society
    Publication date2010
    Pages57-57
    Publication statusPublished - 2010
    EventDanish Physical Society Annual Meeting 2010 - Nyborg, Denmark
    Duration: 22 Jun 201023 Jun 2010

    Conference

    ConferenceDanish Physical Society Annual Meeting 2010
    CountryDenmark
    CityNyborg
    Period22/06/201023/06/2010

    Keywords

    • Magnetic refrigeration
    • Fuel Cells and hydrogen

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