Magnetocaloric properties and Griffiths phase of ferrimagnetic cobaltite CaBaCo₄O₇

Abstract

A study on the magnetocaloric properties of a CaBaCo 4 O 7 polycrystalline cobaltite has been undertaken along with research on the nature of magnetic phase transition. The magnetization as a function of temperature identifies the ferrimagnetic (FIM) to paramagnetic (PM) transition at a Curie temperature of 60 K. Moreover, a Griffiths-like phase is confirmed in a temperature range above T C . The compound undergoes a crossover from the first to second-order ferrimagnetic transformation, as evidenced by the Arrott plots, scaling of the universal entropy curve, and field-dependent magnetic entropy change. The maximum of entropy change is 3 J/kg. K for ΔH = 7 T at T C , and a broadening of the entropy peak with increasing magnetic field indicates a field-induced transition above T C . The analysis of the magnetic entropy change using the Landau theory reveals the second-order phase transition and indicates that the magnetocaloric properties of CaBaCo 4 O 7 are dominated by the magnetoelastic coupling and electron interaction. The corresponding values of refrigerant capacity (RC) and relative cooling power (RCP) are estimated to be 33 and 42 J/kg, respectively.

Theoretical Study of the Multiferroic Properties of Ion-Doped CaBaCo4O7

“…CaBaCo 4 O 7 (CBCO) has garnered significant attention owing to its initial exploration of charge ordering phenomena among Co 2+ and Co 3+ ions. This compound exhibits an orthorhombic distortion [2][3][4][5][6], a phenomenon well-documented in previous studies, which alleviates geometric magnetic frustration evident in both its kagome and triangular layers. Below its magnetic transition temperature (T C ) at 70 K, CBCO manifests a remarkably substantial spin-induced polarization, indicative of a significant ferrimagnetic moment, thereby suggesting the potential for magnetic control over electric polarization [7][8][9][10][11].…”