Structural, magnetic and magnetocaloric effect of pyrochlore iridate Er₂Ir₂O₇

Abstract

The structural, morphological, magnetic and magnetocaloric properties of Er2Ir2O7 are investigated. The X-ray diffraction analysis showed that Er2Ir2O7 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 TC =140K, caused by the appearance of magnetic order of the Ir moments. ΔT (temperature at full width of half maxima) was estimated to be 27K and 40K for magnetic field changes of 40 kOe and 50 kOe, corresponding to the relative cooling power (RCP) values of 98 J/kg and 128 J/kg, respectively. Temperature-averaged Entropy Change (TEC) was calculated for all applied magnetic fields, and found to be slightly lower than (-∆S_M^max) values, indicating less hysteresis loss in the compound Er2Ir2O7 during the magnetic transition. This study provides a new pyrochlore material for MCE magnetocaloric applications.

Enhanced cryogenic magnetocaloric performance and the existence of short-range magnetic correlations in frustrated diamond geometries

“…Along with this, various theoretical investigations indicate that a large MCE can be obtained in frustrated geometries such as Kagome, hyper-Kagome and pyrochlore lattices [8,9]. This has also been confirmed experimentally in various systems, including Gd-based pyrochlores [10][11][12][13].…”

Iso-structural phase transition in pyrochlore iridates (Sm _{1-x}$ Bix)2Ir2O7 (x = 0, 0.02, and 0.10): high-pressure Raman and x-ray diffraction studies

“…the stage for the exploration of novel quantum phenomena and topological phases [1][2][3][4][5][6][7]. By substituting the A site successively with larger rare-earth atoms, the physical properties evolve with the A-site cation radius from magnetic insulating to a complex nonmagnetic metallic behavior [6][7][8][9][10][11][12].…”

“…the stage for the exploration of novel quantum phenomena and topological phases [1][2][3][4][5][6][7]. By substituting the A site successively with larger rare-earth atoms, the physical properties evolve with the A-site cation radius from magnetic insulating to a complex nonmagnetic metallic behavior [6][7][8][9][10][11][12]. In the lanthanide series, from Lu to Gd, iridates show insulating behavior; Eu, Sm, and Nd iridates show a metal-insulator transition (MIT) with the transition temperature varying as a function of rare earth ionic radius [11,13,14].…”