Magnetocaloric effect of ferromagnetic particles

Author

Shull, Robert D.

Author_Institution

Nat. Inst. of Stand. & Technol., Gaithersburg, MD, USA

Volume

29

Issue

6

fYear

1993

fDate

11/1/1993 12:00:00 AM

Firstpage

2614

Lastpage

2615

Abstract

The entropy change accompanying the removal of an applied magnetic field (i.e. the magnetocaloric effect) is calculated for a system of magnetic spins independent of each other and also clustered together into independently acting magnetic particles. Mean-field-theory calculations are made for interacting, single magnetic spins and also for interacting, magnetic particles. In both cases, there are found temperature and field regimes where the entropy changes are larger when the spins are coupled together into nanometer-sized magnetic particles. Entropy change data is shown for a new Gd₃Ga_5-xFe _xO₁₂ (x⩽2.5) magnetic nanocomposite confirming the calculations and possessing magnetocaloric effects larger than the low temperature paramagnetic refrigerant, gadolinium gallium garnet

Keywords

ferrites; ferromagnetic properties of substances; gadolinium compounds; garnets; magnetic properties of fine particles; magnetocaloric effects; nanostructured materials; Gd₃Ga_5-xFe_xO₁₂ magntic nanocomposite; applied magnetic field; entropy change; ferromagnetic particles; field regimes; interacting single magnetic spins; interacting, magnetic particles; low temperature paramagnetic refrigerant; magnetocaloric effect; mean field theory calculations; nanometer sized magnetic particles; Entropy; Garnets; Lattices; Magnetic materials; Magnetic particles; NIST; Paramagnetic materials; Refrigerants; Refrigerators; Temperature;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.280849

Filename

280849