Rare earth-based oxides double perovskites A2NiMnO6 (A= La and gd): Applications in magneto-caloric, photo-catalytic and thermoelectric devices

Abstract

In this paper, we have conducted theoretical work on rare earth-based double perovskites namely, La2NiMnO6 and Gd2NiMnO6, using generalized gradient approximation (GGA) and GGA + U formulations within the full potential linearized augmented plane wave (FP-LAPW) method. It is revealed that using GGA + U computations instead of the conventional GGA method results in a reasonable widening of the band gaps and best fit with the previously explored experimental data with U = 1.5 eV. Further, the band gap values are increased with increasing the U values for the 3d states of Ni and Mn. Moreover, we found that these materials show high magnetic moment, high absorption in the visible and ultraviolet region, and high figure of merit (nearly one for Gd2NiMnO6 at room temperature), hence show their potential in multiple applications such as magneto-caloric, photo-catalytic, solar energy, and thermoelectric devices.