A new sensor for thermodynamic measurements of magnetization reversal in magnetic nanomaterials
Résumé
A sensor for thermal and thermodynamic measurements of small magnetic systems has been designed and built. It is based on a 5 mmthick suspended polymer membrane, which has a very low heat capacity (≈10-6 J/K at nitrogen temperature), and on which a heater and a highly sensitive thermometer are deposited. The sensor properties have been characterized as a function of temperature and frequency. Energy exchanges as small as 1 picojoule (10-12 J) were detected in the 40-300K temperature range. Such values correspond to those required for measuring the thermal signatures occurring during magnetization reversal in very thin samples (typically 10nm thick), which would be deposited on the membrane. It is expected that this method will constitute a powerful tool in view of analyzing magnetization reversal processes in magnetic nanosystems, e.g. exhibiting the exchange-spring and exchange-bias phenomena.
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