中国物理B ›› 2008, Vol. 17 ›› Issue (8): 3087-3092.doi: 10.1088/1674-1056/17/8/053
王 芳, 王光军, 孙继荣, 沈保根
Wang Fang(王芳)†, Wang Guang-Jun(王光军), Sun Ji-Rong(孙继荣), and Shen Bao-Gen(沈保根)
摘要: Effects of Nd-doping on the magnetic properties and magnetocaloric effects (MCEs) of Nd$_{x}$La$_{1 - x}$Fe$_{11.5}$Al$_{1.5}$ 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$_{11.5}$Al$_{1.5}$ characterized by the occurrence of two phase transitions at $\sim$188\,K (PM--AFM) and $\sim $159\,K (AFM--FM). As a result, a table-like MCE (9\,J/kg$\cdot$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.
中图分类号: (Magnetocaloric effect, magnetic cooling)