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.

This study presents a method of producing thick (i.e., in the μm range) polycrystalline Gd free-standing flexible films. Preparation is carried out by sputtering on silicon conventional substrates using tantalum as a buffer and capping layer. Magnetic and magnetocaloric properties show good agreement with data from high-purity bulk Gd, and are not altered by substrate removal. Moreover, the free-standing film is flexible and all the relevant magnetic properties (i.e., Curie temperature T c , saturation magnetization M s , and isothermal entropy change S) are preserved under bending (up to a ε = ±0.78% strain over the two film sides). The technological opportunities heralded by availability of magnetocaloric flexible self-sustaining films are discussed in the conclusions with particular focus on energy-conversion applications (i.e., cooling and thermal energy harvesting). More precisely, the output-power upper bound of an thermal-energy harvester deploying a Gd flexible film with the reported properties is worked-out using a thermal switch model presented elsewhere. The calculations show a potential output able to supply the new generation of IoT wireless devices as well as small medical implants. The result moot Gd free-standing flexible films as a benchmark for a new generation of small high-throughput magnetocaloric energy-conversion devices.