Structure, Electronic, Optical, Magnetic and Magnetocaloric Properties of Sm₂CuMnO₆ Double Perovskite Nanomaterial

This study explores the structural, microstructural, optical, and magnetic characteristics of double perovskite oxide Sm₂CuMnO₆. The sample is prepared in the monoclinic phase with space group P2₁/n using the auto-combustion method. The crystal structure exhibits distortion and tilting. First-principles calculations are conducted using the density-functional theory framework, focusing on electronic structures and density of states. The average crystallite size, particle size and grain size of the sintered sample are 34.42 nm, 36.15 nm and 475 nm respectively. The sample exhibits a direct band gap energy of 1.96 eV. Analysis of the X-ray photoelectron spectra indicates the presence of Sm³⁺, Cu²⁺, and Mn³⁺/Mn⁴⁺ ions in the sample. The DC magnetization study reveals a Curie temperature (T_c) of 50 K for the sample. A non-metallic state resembling a spin glass is detected below 15 K, arising from the competition between antiferromagnetic and ferromagnetic interactions. The maximum value of isothermal magnetic entropy, the relative cooling power and heat capacity are 1.4 J.kg^–1.K^–1, 100.2 J.kg^–1, and 1.35 J.kg^–1.K^–1 at a field change of 70 kOe respectively. The value of Temperature Averaged Entropy Change is 1.36 J.kg⁻¹.K⁻¹ and 1.29 J.kg⁻¹.K⁻¹ for a temperature span of 10 K and 40 K at a field change of 70 kOe.