Correlation between structural parameters and the magnetocaloric effect in epitaxial La0.8Ca0.2MnO3/LaAlO3 thin film

Abstract

Dou, S. X. (2013). Correlation between structural parameters and the magnetocaloric effect in epitaxial La0.8Ca0.2MnO3/LaAlO3 thin film. Journal of Applied Physics, 113 (6), 063508-1-063508-6. Correlation between structural parameters and the magnetocaloric effect in epitaxial La0.8Ca0.2MnO3/LaAlO3 thin film Abstract An epitaxial La0.8Ca0.2MnO3/LaAlO 3 (LCMO/LAO) thin film was fabricated using the pulsed laser deposition technique to evaluate the correlation between the crystal structure and the magnetocaloric effect. In our study, the LCMO film was 200 nm in thickness and appeared to have a strong out-of plane texture. We found that each column in the LCMO thin film layer is a domain which has a different ordering direction. These microscopic feature results in anisotropic properties of magnetization, entropy, and relative cooling power. The film exhibited a paramagnetic-to-ferromagnetic second order phase transition at 249 K. The lack of any hysteresis loss also confirmed that the material is intrinsically reversible. In addition, the large magnetization of the thin film results in an entropy change larger than those of all other perovskite type materials. Consequently, the relative cooling power is significantly enhanced. An epitaxial La 0.8 Ca 0.2 MnO 3 /LaAlO 3 (LCMO/LAO) thin film was fabricated using the pulsed laser deposition technique to evaluate the correlation between the crystal structure and the magnetocaloric effect. In our study, the LCMO film was 200 nm in thickness and appeared to have a strong out-of plane texture. We found that each column in the LCMO thin film layer is a domain which has a different ordering direction. These microscopic feature results in anisotropic properties of magnetization, entropy, and relative cooling power. The film exhibited a paramagnetic-toferromagnetic second order phase transition at 249 K. The lack of any hysteresis loss also confirmed that the material is intrinsically reversible. In addition, the large magnetization of the thin film results in an entropy change larger than those of all other perovskite type materials. Consequently, the relative cooling power is significantly enhanced. V C 2013 American Institute of Physics. [http://dx

Strain dependence of the physical properties of epitaxial La0.7Ca0.3MnO3 thin films grown on LaAlO3 substrates

“…Bibes et al [17] studied the effect of the film thickness on the T C of the LCMO films grown by rf sputtering on STO substrates and found that T C increases from 100 K to 250 K by increasing the film thickness from 10 nm to 100 nm. Debnath et al [18] reported almost the same values of T C in comparison to our LCMO films for a 200 nm thick La 0.8 Ca 0.2 MnO 3 thin film grown by PLD process on LAO substrate. The 60 nm thick film, which is more relaxed compared to the 40 nm thick film, but do not reach that one of the bulk material (T C,bulk ¼ 270 K) [8].…”

Magnetocaloric materials for energy efficient cooling

“…The entropy change in epitaxial 200 nm thick films of La 0.8 Ca 0.2 MnO 3 on LaAlO 3 substrate and La 0.7 Sr 0.3 MnO 3 / SrRuO 3 superlattices is of the same value or even exceeds ΔS observed in bulk counterparts (Zhang et al 2011, Debnath et al 2013. The observed ΔS in epitaxial films exhibits an anisotropy with the values of about 36 kJ m −3 K −1 in the ab plane and 25 kJ m −3 K −1 along the c-axis for a field change of 1 T. Debnath et al (2013) attributed the anisotropy in the MCE to a stronger exchange interaction in the manganite intralayer compared to that in the interlayer, forcing the magnetic moments to lie in the ab plane.…”

Structure and giant inverse magnetocaloric effect of epitaxial Ni-Co-Mn-Al films

“…Otherwise, from [40] one can estimate the RCP of Ni-Co-Mn-In to 135 J kg −1 for μ 0 H = 1.9 T which is similar to the our results for μ 0 H = 2 T. For comparison, Gd shows RCP = 660 J kg −1 for μ 0 H = 5 T (estimated from [33]). Also, the RCP of Ni-Co-Mn-Al is comparable to other promising thin film systems like FeRh [41], MnAs [42], or La 0.8 Ca 0.2 MnO 3 [43], but in contrast to those only consists of common, inexpensive elements.…”