DyTiFe_(11)化合物中自旋再取向的理论解释

THEORETICAL EXPLANATION OF SPIN REORIENTATION IN DyTiFe_(11) COMPOUND

DyTiFe_(11)为铁磁性物质。晶体结构为ThMn_(12)型体心四方结构。室温下易磁化方向为晶体C轴,大约在175K发生自旋再取向。用实验确定了Fe次晶格对磁晶各向异性的贡献,用单离子模型计算了Dy次晶格对各向异性的贡献。研究表明,自旋再取向是两种次晶格磁晶各向异性竞争的结果。

The crystal structure and magnetic properties of DyTiFe_(11) compound have been studied by X-ray diffraction and magnetic measurements. The X-ray diffraction patterns performed on non-aligned and aligned powder samples show that the crystal structure of DyTiFe_(11) has tetragonal body-centered ThMn_(12)-type structure and c-axis is the easy direction of magnetization at room temperature. The results of magnetic measurements show that the Curie temperature T_c is 560K and saturation magnetization at 1.5K is 4.94×10~5A/m. The M-T curves indicate that the spin reorientation begins at about 175K and the angle between the easy direction of magnetization and c-axis is a little larger than 45° at 1.5K. The magnetocrystalline anisotropy constants of Fe sublattice are determined by experiment and that of Dy sublattice are calculated by using single ion model. The results demonstrate that the spin reorientation arises from the competition of magnetocrystalline anisotropy between Dy and Fe sublattices. The spin reorientation is well explained by the theoretical calculation.