Magnetic properties and magnetocaloric effect in Nd_xLa_1-xFe_11.5Al_1.5 compounds

【摘要】 Effects of Nd-doping on the magnetic properties and magnetocaloric effects (MCEs) of Nd x La 1 x Fe 11.5 Al1.5 have been investigated. Substitution of Nd leads to a weakening of the antiferromagnetic (AFM) coupling and an enhancement of the ferromagnetic (FM) coupling. This in turn results in a complex magnetic behaviour for Nd 0.2 La 0.8 Fe 11.5 Al1.5 characterized by the occurrence of two phase transitions at ～188 K (PM–AFM) and ～159 K (AFM–FM). As a result, a table-like MCE (9 J/kg·K) is found in a wide temperature range (160–185 K) for a field change of 0–5 T around the transition temperature, as evidenced by both the magnetic and calorimetric measurements. Based on the analysis of low-temperature heat capacity, it is found that the AFM–FM phase transition modifies the electron density significantly, and the major contribution to the entropy change comes from the electronic entropy change.更多还原

【Abstract】 Effects of Nd-doping on the magnetic properties and magnetocaloric effects (MCEs) of Nd x La 1 x Fe 11.5 Al1.5 have been investigated. Substitution of Nd leads to a weakening of the antiferromagnetic (AFM) coupling and an enhancement of the ferromagnetic (FM) coupling. This in turn results in a complex magnetic behaviour for Nd 0.2 La 0.8 Fe 11.5 Al1.5 characterized by the occurrence of two phase transitions at ～188 K (PM–AFM) and ～159 K (AFM–FM). As a result, a table-like MCE (9 J/kg·K) is found in a wide temperature range (160–185 K) for a field change of 0–5 T around the transition temperature, as evidenced by both the magnetic and calorimetric measurements. Based on the analysis of low-temperature heat capacity, it is found that the AFM–FM phase transition modifies the electron density significantly, and the major contribution to the entropy change comes from the electronic entropy change.更多还原