Structural, Magnetic and Magnetocaloric Properties of Electron-Doped Manganite La0.9Hf0.1MnO3

We have prepared an electron-doped manganite La0.9Hf0.1MnO3 (LHMO) by a solid state reaction method, and then systematically investigated its structural, magnetic and magnetocaloric properties. The analysis of XRD data based on Rietveld refinement reveals that the LHMO sample crystallizes in the rhombohedral structure with a space group of R3¯C. M(T) data show that the ferromagnetic–paramagnetic (FM–PM) transition temperature (TC) is 240 K. Under a magnetic field change of 5 T, the magnetic entropy change (−ΔSM) exhibits a peak value of −ΔSMmax(T)  =  4.27 J kg−1 K−1 with a relative cooling power value of 228.36 J kg−1 in the vicinity of the TC. These results indicate that the electron-doped manganite LHMO can be regarded as a suitable material to be used in active magnetic refrigeration near sub-room temperatures. Both an Arrott plots analysis and phenomenological universal curves confirm that the FM–PM transition in the LHMO is of a second order. In addition, the temperature-dependent  −ΔSM can be well understood according to Landau’s theory of phase transition.