Abstract
Particle size as an effective tool for controlling the magnetic and magnetocaloric properties of Pr0.6Sr0.4MnO3 samples has been studied. In the present work, a direct influence of particle size on the magnitude of magnetization and magnetic transition temperature, TC, can be seen. The TC drops from 309 to 242 K, while the saturation magnetization (MS) decreases from 3.6 to 0.5 μB/f.u. as the particle changes from 120 to 9 nm. Concurrently, coercivity (HC) 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.
Highlights
Perovskites of the generic form, AMnO3 (A = rare earth, transition or post-transition metal ion), are of interest for technological applications as well as for a basic understanding of the physical properties [1,2,3]
We had studied the influence of particle size reduction on the magnetism of La0.7Sr0.3MnO3 (LSMO) where we noticed a systematic decrease in the net magnetization with a decrease in particle size along with the appearance of Griffith’s like singularity [38]
Magnetic measurements were carried out using Quantum Design Superconducting Quantum Interference Device (SQUID) Vibrating Sample Magnetometer (VSM) in magnetic fields up to ± 70 kOe and temperature down to 2 K
Summary
The material shows a structural transition, (Ts) at & 89 K which is observed as a drop in magnetization within the FM state of the material [34,35,36,37] This results in the coexistence of normal and inverse magnetic entropy change in the single matrix which is very interesting as magnetic cooling of the sample can be achieved through both adiabatic magnetization and demagnetization in different temperature regimes which in turn enables the extension of the active region for magnetic refrigeration [34]. We had studied the influence of particle size reduction on the magnetism of La0.7Sr0.3MnO3 (LSMO) where we noticed a systematic decrease in the net magnetization with a decrease in particle size along with the appearance of Griffith’s like singularity [38] Even though both PSMO and LSMO are room temperature FM, La1-xSrxMnO3 belongs to the category of large bandwidth manganite exhibiting FM over wide doping concentration of Sr2?
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