Study of A-Site Disorder Dependent Structural, Magnetic, and Magnetocaloric Properties in La_0.7-xSm_xCa_0.3MnO₃ Manganites

Abstract

We report studies on the magnetocaloric effect of samarium doped lanthanum manganites with different Sm-concentrations. Polycrystalline La0.7-x Sm x Ca0.30MnO3 (0≤x≤0.3) samples were prepared using the conventional solid-state reaction method with phase purity and structure confirmed using X-ray diffraction. Temperature dependent magnetization measurements and Arrott analysis reveal first order ferromagnetic transition in parent sample and second order ferromagnetic transition in doped sample with Curie temperature decreasing progressively with increasing Sm concentration from ∼182 K for x = 0.05 to 109 K for x = 0.30. A large magnetic entropy change (∼1.75 J kg-1 K-1 at 0.5 T) has been observed in La0.7Ca0.3MnO3 sample, and is greatly suppressed as a function of disorder caused by Sm doping. This is ascribed to the gradual loss of first-order ferromagnetic transition. This investigation suggests that La0.7-x Sm x Ca0.30MnO3 compounds can be used as a potential magnetic refrigerating material with wide range of temperature.

Disorder-driven phase transition in La0.37D0.30Ca0.33MnO3 (D = Bi, Sm) manganites

“…It has been reported that La 0.7−x Sm x Ca 0.3 MnO 3 with x ≥ 0.05 show second order FM -PM transition. 13 It is reported that single crystal of La 0.7 Sr 0.3 MnO 3 (LSMO) shows second-order phase transition from FM-PM with critical exponents β = 0.37 ± 0.045, γ = 1.22 ± 0.03 and δ = 4.25 ± 0.0, which are close to values predicted for conventional Heisenberg ferromagnet. 49 Whereas, La 1−x Ca x MnO 3 manganite undergoes first-order FM-PM transition in the composition range 0.3 ≤ x ≤ 0.4.…”

“…The decrease in the unit-cell volume for these samples compared to La 0.67 Ca 0. 33 13,15,18 From the refinement the estimated atomic positions for the samples are listed in Table I. Microstructure of the samples Fig.…”

“…9 The disorder induced second-order FM-PM phase transition is reported in the literature. [12][13][14] There are reports on the effect of Bi 11,[15][16][17][18][19][20][21] and Sm 13,[22][23][24] doping at La-site in La-manganites. M. C. Walsh et al 11 have investigated magnetic and electronic properties of La 0.67−x Bi x Ca 0.33 MnO 3 (x ≤ 0.16).…”

“…The evolution different properties with Bi doping can be due to the effect of 6 s loan pair of Bi 3+ ions. 17 M. Anwar et al 13 studied the disorder effects on structure, magnetic and magnetocaloric properties in La 0.7−x Sm x Ca 0.3 MnO 3 (0 ≤ x ≤ 0.3)manganites. The studies on these compounds confirm the first order FM transition in undoped sample and second order FM transition in doped sample.…”

Magnetocaloric Properties in La0.5Ca0.45K0.05MnO3, Pr0.5Sr0.45K0.05MnO3, and Nd0.5Sr0.45K0.05MnO3 Manganites

“…A prominent feature of these materials is colossal magnetoresistance (CMR) effect, which has been extensively studied in the last few decades [8][9][10][11][12]. Apart from the CMR effect, these compounds have also been found to exhibit the magnetocaloric effect (MCE) under a moderate applied magnetic field [13,[13][14][15][16][17].…”