Gd–Pt–In <i>In Situ</i> Composite Exhibiting Enhanced Relative Cooling Power and Broad Magnetocaloric Effect

In this study, a Gd-Pt-In composite was synthesized by arc melting. Powder X-ray diffraction, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) analyses confirmed the composite composition formed by a matrix phase of GdPtIn, comprising 76% of the sample, and a dispersed phase (21%) formed by GdPt. Magnetic and specific heat measurements revealed two ferromagnetic transitions in the composite at 67 and 63.5 K. These successive transitions provide a very broad curve for both the magnetic entropy change (-Δ<i>S</i> _M) and adiabatic temperature change (Δ<i>T</i> _ad) magnetocaloric parameters, generating a wide temperature range with a significant magnetocaloric effect (MCE) and a substantial relative cooling power (RCP). For a magnetic field change (Δ<i>H</i>) of 50 kOe, the maximum magnetic entropy change (-Δ<i>S</i> _M ^max) reached 6 J/kg K, with a corresponding RCP value of 368 J/kg. The excellent magnetocaloric properties of the Gd-Pt-In composite position it as a promising candidate for low-temperature magnetic refrigeration applications. Furthermore, these findings offer valuable insights for the ongoing search for effective refrigerant materials, particularly those exhibiting multiple successive magnetic phase transitions.