Magnetic properties and magnetocaloric effect in La0.7Nd0.3Fe13−xSix compounds

The structural, magnetic and magnetocaloric properties in the cubic NaZn13-type La0.7Nd0.3Fe13−xSix compounds with x=1.2, 1.4, 1.6 and 1.8 are reported. All of the investigated samples are ferromagnetically ordered. The Fe saturation moment at 5 K is independent of Si concentration, having a value of 2.05±0.09 μB, which suggests a high degree of localization. The Curie temperatures increase almost linearly with the increase in silicon concentration. The large ΔSM values obtained for samples with low Si content are mainly due to the first-order character of the transition at TC. The field-induced transition above TC causes an asymmetric broadening of the ΔSM peak towards higher temperatures for higher applied fields. With increasing Si content, the first-order character of the transition at TC is diminished, leading to lower ΔSM values. The potential use of these materials in magnetic refrigeration is discussed. - Graphical abstract: Transition from a first-order to a second-order magnetic phase transition at TC on La0.7Nd0.3Fe13−xSix. Highlights: ► Magnetic properties and magnetocaloric effect in La0.7Nd0.3Fe13−xSix compounds are reported. ► Transition from a first-order to a second-order type magnetic phase transition at TC with increasing silicon content. ► Itinerant electronic metamagnetic transition above the Curie temperature. ► High values of the magnetic entropy changes in 2 T magnetic field.