Near room temperature magnetocaloric properties and critical behavior of binary Fe_xCu_100−xNanoparticles

Low cost, rare earth-free magnetocaloric materials are being intensively studied for near room temperature, energy efficient, “green”, magnetic cooling applications. We report the magnetocaloric properties and critical analysis of ball milled Fe_xCu_100-xnanoparticles for x = 30 to 35. Magnetization measurements of Fe_xCu_100-xnanoparticles show soft ferromagnetic behavior at room temperature with small coercivity (H_C) values. The Curie temperature (T_C) could be tuned over a wide temperature range, from 268 K to 360 K, with varying Fe content. The positive slope of the Arrott plots confirms the second order nature of the magnetic transition. Critical analysis of the magnetic phase transition using modified Arrott plots supports the 3D-Heisenberg model. The magnetocaloric effect (MCE) i.e., change in isothermal magnetic entropy (ΔS_m) and relative cooling power (RCP) of Fe_xCu_100-xnanoparticles is comparable to that of other Fe based alloys. The high thermal conductivity, soft ferromagnetic behavior and magnetocaloric properties of Fe_xCu_100-xnanoparticles are potentially useful for low cost, rare earth element free magnetic cooling applications.