Near-room-temperature magnetocaloric properties at 1.5 T coupled with relaxor dielectric properties in La2CoMnO6 nanoparticles

Abstract

Achieving high magnetic entropy change at low magnetic fields near room temperature may pave the way to attaining room temperature magnetic refrigeration. We report herein on high magnetic entropy change at 1.5 T around 291 K in La2CoMnO6 manganite nanoparticles. The magnetic, magnetocaloric, and dielectric properties of La2CoMnO6 nanoparticles of sizes D = 30–40 nm are reported. Powder X-ray diffraction analysis and Raman spectra have confirmed the co-existence of a monoclinic ordered phase and a partially disordered phase. Magnetization measurements have showna long-range ferromagnetic to paramagnetic transition at a Curie temperature of 291.9 K. A maximum magnetocaloric entropy change of 0.88 J kg−1 K−1 has been achieved upon application of a 1.5 T external magnetic field. Dielectric measurements have shown relaxation behavior and a high dielectric constant. The detailed electrical conduction mechanism is explained in terms of various polaron hopping mechanisms. The mutual origin of magnetocaloric and dielectric relaxor behavior in La2CoMnO6, along with its high dielectric constant, confirms that there is strong coupling between the magnetic and dielectric properties of this material, making it suitable for multifunctional applications.