Study of physical properties of a ferrimagnetic spinel CuMnO: spin dynamics, magnetocaloric effect and critical behavior.

The present work reports a detailed study of the spin dynamics, magnetocaloric effect and critical behaviour near the magnetic phase transition temperature, of a ferrimagnetic spinel CuMnO. The dynamic magnetic properties investigated using frequency-dependent ac magnetic susceptibility fitted using different phenomenological models such as Neel-Arrhenius, Vogel-Fulcher and power law, strongly indicate the presence of a cluster-glass-like behavior of CuMnO at 40 K. The magnetization data have revealed that our compound displays an occurrence of second-order paramagnetic (PM) to ferrimagnetic (FIM) phase transition at the Curie temperature = 80 K as the temperature decrease. In addition, the magnetic entropy change (Δ ) was calculated using two different methods: Maxwell relations and Landau theory. An acceptable agreement was found between both sets of data, which proves the importance of both electron interaction and magnetoelastic coupling in the magnetocaloric effect (MCE) properties of CuMnO. The relative cooling power (RCP) reaches 180.13 (J kg) for an applied field at 5 T, making our compound an effective candidate for magnetic refrigeration applications. The critical exponents , and as well as transition temperature were extracted from various techniques indicating that the magnetic interaction in our sample follows the 3D-Ising model. The validity of the critical exponents is confirmed by applying the Windom scaling hypothesis.