Magnetic and Magnetocaloric Properties of Multiferroic Oxides Gd0.5Y0.5MnO3 and Eu0.5Dy0.5MnO3

摘要

In this article, crystal structure, magnetism, heat capacity, magnetocaloric effect (MCE), and electrical resistivity of mixed rare-earth Gd _0.5 Y _0.5 MnO ₃ and Eu _0.5 Dy _0.5 MnO ₃ manganites have been studied. Temperature-dependent magnetization $M(T)$ measurements suggest an antiferromagnetic order just below 6 K in Gd _0.5 Y _0.5 MnO ₃ , while no magnetic transition has been observed down to 5 K in Eu _0.5 Dy _0.5 MnO ₃ . Heat capacity data reveal anomalies at 40 and 42 K in Gd _0.5 Y _0.5 MnO ₃ and Eu _0.5 Dy _0.5 MnO ₃ , and these may correspond to Mn magnetic order as previously reported. The magnetization values are 2.8 and $3~mu _{mathrm {B}}$ /f.u. in 70 kOe field at 5 K for Gd _0.5 Y _0.5 MnO ₃ and Eu _0.5 Dy _0.5 MnO ₃ , respectively. MCE has been estimated in terms of isothermal magnetic entropy change ( $Delta S_{mathrm {m}}$ ) at low temperatures. The maximum values of $Delta S_{mathrm {m}}$ are about −11 and −6.2 J kg $^{-1},,ext{K}^{-1}$ , respectively, for Gd _0.5 Y _0.5 MnO ₃ and Eu _0.5 Dy _0.5 MnO ₃ samples for a field change of 70 kOe at 8 K. Electrical resistivity of Gd _展开▼