Structural, magnetic and magnetocaloric effect of pyrochlore iridate Er 2 Ir 2 O 7

The structural, morphological, magnetic and magnetocaloric properties of Er 2 Ir 2 O 7 are investigated. The x-ray diffraction analysis showed that Er 2 Ir 2 O 7 has a cubic structure with the Fđ3m space group. Using Williamson-Hall (W-H) plot, the crystallite size was found to be smaller than that obtained from the SEM image. Magnetic measurements revealed a weak ferromagnetic transition at T C = 140 K, caused by the appearance of magnetic order of the Ir moments. Δ T (temperature at full width of half maxima) was estimated to be 27 K and 40 K for magnetic field changes of 40 kOe and 50 kOe, corresponding to the relative cooling power ( RCP ) values of 98 J kg −1 and 128 J kg −1 , respectively. Temperature-averaged Entropy Change ( TEC ) was calculated for all applied magnetic fields, and found to be slightly lower than − Δ S M max values, indicating less hysteresis loss in the compound Er 2 Ir 2 O 7 during the magnetic transition. This study provides a new pyrochlore material for MCE magnetocaloric applications.