A new sensor for thermodynamic measurements of magnetization reversal in magnetic nanomaterials

Olivier Bourgeois (1) , Cristina Macovei (2) , Emmanuel André , Jean-Luc Garden (3) , Jacques Chaussy (1) , Dominique Givord (2)

1 NEEL - TPS - Thermodynamique et biophysique des petits systèmes
2 NEEL - MNM - Micro et NanoMagnétisme
3 NEEL - Institut Néel

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.

Mots clés: Magnetocaloric effect; Specific heat measurements; Microsystems; Thermal properties of thin film

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Olivier Bourgeois, Cristina Macovei, Emmanuel André, Jean-Luc Garden, Jacques Chaussy, et al.. A new sensor for thermodynamic measurements of magnetization reversal in magnetic nanomaterials. Journal of Magnetism and Magnetic Materials, 2007, 316, pp.e94-e96. ⟨10.1016/j.jmmm.2007.02.037⟩. ⟨hal-00312702⟩