Magnetic and magnetocaloric properties of CuMn₂O₄ and Mn₃O₄ composite system

Polycrystalline CuMn₂O₄ is synthesized by solid state reaction method. Structural and magnetization studies reveal that the sample is multiphase with CuMn₂O₄ as primary phase and Mn₃O₄ as secondary phase. Magnetocaloric properties such as isothermal magnetic entropy change (−ΔS _M) and refrigerant capacity (RC) are evaluated from isothermal magnetization data. Value of isothermal magnetic entropy change ($|\Delta S_M|$) in the 40–80 K temperature range is 3.5–4.6 J kg⁻¹K⁻¹, for a field change of ΔH = 70 kOe. Value of refrigeration capacity (RC) evaluated for the same field change (ΔH = 70 kOe) is ∼190 J/kg for the T _cold and T _hot pair of 40 and 90 K respectively. Also value of $|\Delta S_M|$ remains almost constant over a broad temperature range of 60–80 K. (paper)