Large magnetocaloric effect in a La0.7Ca0.3MnO3 single crystal

TLDR

The study examines the magnetocaloric effect in a La₀.₇Ca₀.₃MnO₃ single crystal undergoing a first‑order transition at ~227 K, measuring ΔSₘ ≈ 6.42 J kg⁻¹ K⁻¹ and ΔTₐd ≈ 4.76 K for ΔB = 5 T, noting a more uniform ΔSₘ distribution than gadolinium. The single‑crystal manganite exhibits a larger, uniformly distributed MCE than its polycrystalline counterpart, making it attractive for Ericsson‑cycle magnetic refrigeration and household AMR, and its ΔSₘ near the Curie temperature is well described by a molecular‑field model.

Abstract

We report the results of a thorough study of the magnetocaloric effect (MCE) in a La0.7Ca0.3MnO3 single crystal, which undergoes a first-order magnetic phase transition at ∼227 K. The magnetic entropy change ΔSM and the adiabatic temperature change ΔTad reach, respectively, ∼6.42 J/kg K and 4.76 K for ΔB=5 T and even if both are smaller than those exhibited by gadolinium (∼9.8 J/kg K and ∼11.7 K), the ΔSM distribution here is much more uniform than that of gadolinium and polycrystalline manganites. This is desirable for an Ericson-cycle magnetic refrigerator. The MCE is larger in the single-crystalline manganite compared to the polycrystalline one. The manganite single crystal has large ΔSM induced by low magnetic field change, which is beneficial for the household application of active magnetic refrigerant (AMR) materials. All these make the lanthanum manganite single crystal an attractive candidate as a working substance for AMR. The molecular field model provides a fairly good description of the magnetic entropy change at temperatures close to the Curie temperature.