Enhanced Magnetocaloric properties of transition metal-doped Mn3O4 compounds

Authors

• F. Azim, University of Memphis
• J. Mohapatra, The University of Texas at Arlington
• A. Sharmin, University of Memphis
• P. Joshi, The University of Texas at Arlington
• J. P. Liu, The University of Texas at Arlington
• S. R. Mishra, University of Memphis

Abstract

This study reports the magnetic and magnetocaloric properties of transition-metal-doped Cr-Mn3O4 and Co-Mn3O4 synthesized via a facile autocombustion method. The X-ray diffraction (XRD) results confirmed the tetragonal structure of Mn3O4, Co-Mn3O4, and the cubic structure of Cr-Mn3O4. X-ray photoelectron spectroscopy (XPS) confirmed the oxidation states of individual transition-metal ions. The Curie temperatures, T c , measured from Magnetization vs. Temperature curves, are 53 and 182 K for Cr-Mn3O4 and Co-Mn3O4, respectively. High coercivity, Mn3O4, ( H c ∼ 10 kOe) turned soft with reduced H c ∼ 9.2 and 2.8 kOe upon Co²⁺ and Cr³⁺ doping. The second-order phase transition nature of doped compounds was confirmed from the Arrot plots. Electron spin resonance (ESR) confirmed the paramagnetic nature of these compounds at room temperature. The maximum change in magnetic entropy, │ ΔS Max │, and corresponding relative cooling power, RCP, are recorded as 2.41, 7.63, 4.51 Jkg⁻¹ K⁻¹ and 40, 256, 74 Jkg⁻¹ for Mn3O4, Cr-Mn3O4, and Co-Mn3O4 compounds, respectively. Nearly 200 % and 87 %, a record increase in │ ΔS Max │ value, is displayed upon Cr and Co doping in Mn3O4 compared to the pure Mn3O4 compound. The improved MCE performance of these doped Mn3O4 compounds makes them promising candidates for magnetic refrigeration applications.

Publication Title

Journal of Magnetism and Magnetic Materials

Recommended Citation

Azim, F., Mohapatra, J., Sharmin, A., Joshi, P., Liu, J., & Mishra, S. (2026). Enhanced Magnetocaloric properties of transition metal-doped Mn3O4 compounds. Journal of Magnetism and Magnetic Materials, 638 https://doi.org/10.1016/j.jmmm.2025.173739