Large magnetocaloric effect near room temperature in $${\mathbf{L}\mathbf{a}}_{0.67}{(\mathbf{S}\mathbf{r},\mathbf{K}/\m
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Large magnetocaloric effect near room temperature in La0:67ðSr; K=PbÞ0:33MnO3 manganite nanomaterials Sonali Biswas1 and Sunita Keshri1,* 1
Department of Physics, Birla Institute of Technology, Mesra, Ranchi, Jharkhand 835215, India
Received: 20 August 2020
ABSTRACT
Accepted: 15 October 2020
The magnetic and magnetocaloric properties of La0:67 Sr0:33 MnO3 (LSMO), La0:67 Sr0:23 K0:10 MnO3 (LSKMO), and La0:67 Sr0:23 Pb0:10 MnO3 (LSPMO) manganite nanomaterials were investigated. The superparamagnetic behavior of these nanomaterials was analyzed using the log-normal weighted Langevin function. Large change in magnetic entropy (DSM ) and relative cooling power (RCP) were observed near the Curie temperature, TC , for all samples. The maximum change 1 1 in entropy (DSmax under 7 T magnetic M ) is found to be 5.0, 5.3, and 6.2 Jkg K field for LSMO, LSKMO, and LSPMO samples, respectively, whereas the corresponding RCP values are 400, 440, and 325 Jkg1 . The isothermal magnetization data were analyzed thoroughly, using Arrott plots according to Banerjee’s criterion. Moreover, the critical exponents (b, c and dÞ were calculated using the modified Arrott plot. The Widom scaling relation was studied to confirm the dependability of these critical exponents. The magnetocaloric effect was also analyzed by considering the Landau theory. Our findings indicate that these samples can have promising applications for magnetic refrigeration.
Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Perovskite-structured manganites with chemical formula R1x Ax MnO3 (R = trivalent rare earth element and A = alkaline earth) have revived immense attention due to their interesting transport, magnetic and structural behaviors as well as potential applications in recent technology [1–5]. These materials exhibit numerous functional properties such as colossal magnetoresistance (CMR) effect, superparamagnetism, and magnetocaloric effect (MCE). Ferromagnetic behavior (below Curie temperature, TC ) of
these manganites becomes superparamagnetic when its particle size is small, and the magnetic spins get influenced by thermal fluctuation. For such nanomaterials, thermal fluctuation is strong enough to demagnetize a previously saturated assembly spontaneously. This causes a large saturation magnetization as well as a non-hysteretic M–H curve with zero remanence and coercivity. These nanomaterials have been widely studied for different biomedical applications [6–9]. Apart from this, in recent years, perovskite manganites have attained enormous interest in exploring the possibility of making them
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https://doi.org/10.1007/s10854-020-04694-9
J Mater Sci: Mater Electron
suitable for magnetic refrigeration with a huge change in magnetic entropy over a broad temperature span. Magnetocaloric effect is more effective and eco-friendly technique of refrigeration in comparison to the other conventional refrigeration technology of traditi
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