Magnetocaloric Gadolinium thick films for energy harvesting applications

Abstract

Magnetization, Curie temperature and isothermal entropy change have been measured in Gadolinium 3 μm thick films. We present the comparison between the structural and magnetic properties of samples deposited either at room temperature or at 550°C onto silicon substrate (100) with a thermally oxidized layer. The results are discussed using as a reference, data from bulk Gd single crystals. As compared to bulk values, the room temperature grown film shows lower Curie temperature (∼280 K) and weaker entropy change (∼6.8 Jkg-1K-1) under application of magnetic field ramp from 0 to 5 Tesla. On the contrary the 550-C deposited film shows a Curie temperature (∼293 K) and a maximum isothermal entropy change (∼8.9 Jkg-1K-1) both in good agreement with values expected for bulk samples. The behavior of the room temperature deposited samples are briefly discussed and compared with similar effects observed in bulk samples with different degree of purity and homogeneity.