摘要
当x<0.5时,Nd_2(Fe_(1-x)Mn_x)_(14)B可形成四方晶体结构,空间群为P4_2/mnm。在低温下,该赝三元化合物的大块铸态样品具有高矫顽力。此矫顽力不依赖于热处理等工艺过程,因此具有内禀性质。内禀矫顽力_iH_c与样品的成分有关。Nd_2(Fe_(1-x)Mn_x)_(14)B的起始磁化曲线具有传播场H_p,并且H_p的数值与_iH_c接近。这表明内禀矫顽力是由畴壁钉扎造成的。研究了_iH_c与温度的变化关系,并估算了钉扎位垒的强度。测量了Nd_2(Fe_(1-x)Mn_x)_(14)B的居里温度和饱和磁化强度。在此赝三元化合物中,交换作用随Mn对Fe的替换而急剧降低。这使得畴壁厚度变窄。Nd_2(Fe_(1-x)Mn_x)_(14)B的磁化和反磁化行为可用窄畴壁的特征来解释。
Nd_2(Fe_(1-x)Mn_x)_(14)B crystallize in the tetragonal structure, space group P42/mnm, when x < 0.5. A large coercive force has been observed at T = 1.5K in the as-cast bulk samples of the pseudoternary compounds. It does not depend on treatment such as milling, sintering and annealing. Accordingly, the coercive force must be intrinsic. The intrinsic coercive force iHc shows a composition dependence. The form of the virgin magnetization curve is characterized by a propagate field H_p. The value of H_p is close to that of iHC, indicating that the intrinsic coercive force is created by domain wall pinning. The temperature dependence of iHc were studied. The strength of the pinning potential barrier was estimated. The Curie temperature and saturation magnetization of Nd_2(Fe_(1-x)Mn_x)_(14)B were measured. The exchange interaction in the pseudoternary compounds decreases dramatically with substitution of Mn for Fe. That results in a decrease of the thickness of domain walls. The magnetization and demagnetization behaviors in Nd_2(Fe_(1-x)Mn_x)_(14)B can be understood in terms of narrow domain walls.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
1990年第4期649-655,共7页
Acta Physica Sinica
基金
国家自然科学基金
