Giant low-field magnetocaloric effect and refrigerant capacity in reduced dimensionality EuTiO₃ multiferroics

Engineering magnetic materials into a thin film form while preserving its excellent magnetocaloric response is essential in the development of miniature magnetic coolers. We demonstrate how this can be achieved in the case of EuTiO₃ – an emerging multiferroic material. Unlike conventional cases where reduced dimensionality considerably decreased the magnetic entropy change (ΔS_M) and hence the refrigerant capacity (RC), we show the large low-field enhancements of ΔS_M and RC in a ∼100 nm thick nanocrystalline EuTiO₃ film (ΔS_M ∼ 24 J kg⁻¹K⁻¹ and RC = 152 J kg^-1 for μ₀ΔH = 2 T) relative to its single crystal counterpart (ΔS_M ∼ 17 J kg⁻¹K⁻¹ and RC ∼ 107 J kg^-1 for μ₀ΔH = 2 T). The nanocrystalline EuTiO₃ film is an excellent candidate for cryogenic magnetic refrigeration. From our study, a new approach for improving both MCE and RC in magnetic nanomaterials is proposed, which will stimulate further research on magnetocaloric thin films and related cooling devices.