Tuning magnetic and magnetocaloric properties of Pr_0.6Sr_0.4MnO₃ through size modifications

Particle size as an effective tool for controlling the magnetic and magnetocaloric properties of Pr_0.6Sr_0.4MnO₃ samples has been studied. In the present work, a direct influence of particle size on the magnitude of magnetization and magnetic transition temperature, T_C, can be seen. The T_C drops from 309 to 242 K, while the saturation magnetization (M_S) decreases from 3.6 to 0.5 μ_B/f.u. as the particle changes from 120 to 9 nm. Concurrently, coercivity (H_C) exhibits a drastic rise emphasizing the enhanced surface disorder in the nanoparticles. Another interesting observation is in the magnetic entropy change, ΔS, which though decreases in magnitude from 5.51 to 3.90 J/Kg-K as particle size decreases from 120 to 30 nm, but the temperature range of ΔS (i.e., relative cooling power, RCP) increases from 184.33 to 228.85 J/Kg. Such interplay between magnitude and wider temperature range of ΔS, which can be fine-tuned by particle size, provides an interesting tool for using surface spin disorder, as a control mechanism in modifying physical properties.