Tailoring the magnetic entropy change towards room temperature in Sr-site deficient La0.6Dy0.07Sr0.33MnO3 manganite

Abstract

The effects of Sr-site deficiency on the structural and magnetic properties and magnetic entropy change of La_0.6Dy_0.07Sr_0.33−yMnO_3−δ (y = 0 and 0.09) compounds were investigated in the present study. Rietveld refinement confirms the phase purity and rhombohedral crystal structure of the compounds. Mixed valence states of Mn²⁺/Mn³⁺/Mn⁴⁺ ions were confirmed in the Sr-deficient compound from the X-ray photoelectron spectroscopy technique. A second order ferromagnetic–paramagnetic transition was observed in both compounds. La_0.6Dy_0.07Sr_0.33MnO₃ shows a magnetic entropy change of 4.51 J kg⁻¹ K⁻¹ at 326 K, and the Sr-deficient compound, i.e., La_0.6Dy_0.07Sr_0.24MnO_3−δ, exhibit a ΔS_M of 3.57 J kg⁻¹ K⁻¹ at 302 K under a 50 kOe field change. Thus, in the present case, we have achieved a significant value of ΔS_M near room temperature in the Sr-deficient compound, which could be a potential candidate for room temperature magnetic refrigeration applications.