Formation of Tetrahedrally Close-Packed Structures in Tb-Fe and Co-Pd Nanocrystalline Films

摘要

The crystal structure of Tb_(30)Fe_(70) and Co_(50)Pd_(50) nanocrystalline films with strong magnetic anisotropy perpendicular to the film plane (K_⊥ ～ 10~6 erg/cm_3) is investigated using electron diffraction and transmission electron microscopy. All the studied films in the initial nanocrystalline phase undergo an explosive crystallization with the formation of dendrite structures. It is demonstrated that, after crystallization, the Tb-Fe and Co-Pd films exhibit a tetrahedrally close-packed atomic structure that has no analogs among these materials in the equilibrium state. The internal stresses in the films under investigation are estimated from an analysis of the bend extinction contours in the electron microscope images. The inference is made that strong perpendicular magnetic anisotropy can be associated with magnetostriction anisotropy due to the specific features of the film structure.