Consequences of the magnetocaloric effect on magnetometry measurements

TitleConsequences of the magnetocaloric effect on magnetometry measurements
Publication TypeJournal Article
Year of Publication2010
AuthorsHansen BR, Bahl CRH, Kuhn LT, Smith A, Gschneidner KA, Pecharsky VK
Journal TitleJournal of Applied Physics
Date Published08/15
ISBN Number0021-8979
Accession NumberISI:000281857100096
Keywordsco, gd5si2ge2, la(fe, powder-metallurgy, temperature

Magnetization curves recorded at high sweep-rates on magnetic materials near a phase transition temperature can be affected by temperature changes in the material due to the magnetocaloric effect. This change in the sample temperature is a result of the quasiadiabatic conditions that can occur under such conditions and we demonstrate its effects on magnetization curves of two magnetocaloric materials, La(Fe0.945Co0.055)(11.9)Si-1.1 and Gd5Si2Ge2. We show how a quantity calculated from isothermal magnetization curves, the magnetic entropy change, Delta S-M, is affected by the erroneous data. As Delta S-M is a measure of the magnetocaloric effect, the discrepancies demonstrated here are more severe close to a peak in Delta S-M, which is precisely the quantity that is of interest and reported on in the literature from possibly erroneous magnetization data. We also demonstrate how, through simple measurements and without a direct measurement of the sample temperature, one can determine an appropriate sweep-rate of the magnetic field. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3466977]

URL<Go to ISI>://000281857100096