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本文研究了Nd_2Fe_(14)B单晶在不同温度下的自发磁致伸缩及其各向异性。发现沿c轴及垂直c轴方向的自发磁致伸缩差别较大,在室温下,其自发磁致伸缩系数值分别为1.1×10~(-3)和4.3×10~(-8)。根据平均分子场理论阐述了产生自发磁致伸缩的机理,并说明了Nd_2Fe(14)B单晶在不同方向的不同自发磁致伸缩。自发磁致伸缩效应起源于原子中电子间的交换相互作用,发现其变化规律与M_8~2(T)的变化规律一致。沿着不同的方向,由于原子排列情况的不同而呈现出不同的自发磁致伸缩。当样品对应于slate-Bethe曲线的不同位置时,由于交换相互作用的变化,表现出正的或负的自发磁致伸缩。
In this paper, the spontaneous magnetostriction and anisotropy of Nd_2Fe_ (14) B single crystal at different temperatures are studied. It is found that the spontaneous magnetostriction varies greatly along the c-axis and the vertical c-axis. The values of spontaneous magnetostriction at room temperature are 1.1 × 10 -3 and 4.3 × 10 -8, respectively. According to the theory of average molecular field, the mechanism of spontaneous magnetostriction was expounded and the different spontaneous magnetostriction of Nd 2 Fe (14) B single crystals in different directions was described. The spontaneous magnetostriction effect originated from the exchange interaction between atoms in the atom, and found that the change rule was consistent with that of M_8 ~ 2 (T). In different directions, different spontaneous magnetostriction appears due to the different atomic arrangement. When the sample corresponds to different positions of the slate-Bethe curve, either positive or negative spontaneous magnetostriction appears due to the change in exchange interaction.