Effects of size reduction on the magnetic and magnetocaloric properties of NdMn2Ge2 nanoparticles prepared by high-energy ball milling

A nanostructured NdMn2Ge2 sample is prepared by a high-energy ball-milling technique. The structural and magnetic properties of ball-milled nanopowder have been studied by high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), magnetic force microscopy (MFM), and magnetization measurements. According to the HRTEM results, the particle size of the nanoparticles changes from 5 to 11 nm. Curie and spin-reorientation temperatures are found to be 328 and 208K from the temperature-dependent magnetization measurements, respectively. The maximum magnetic entropy change values are about -0.4 and -1.10 J kg(-1)K(-1) for Delta H = 2T around the spin-reorientation (TSR) and Curie (TC) temperatures, respectively. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim