Crystallization behavior of Co32Fe48B20 electrode layers in annealed magnetic tunnel junctions

Abstract

The magnetoresistance (MR) ratio of magnetic tunnel junctions (MTJs) depends on the structure and characteristics of the interface between the ferromagnetic electrode and insulating layer. In order to understand the role of the amorphous CoFeB layer, the MTJs of the following three different pinned layers (PLs) were used: CoFeB (PL1), CoFe/CoFeB/CoFe (PL2) and CoFe (PL3). The MTJs with PL1 and PL2 showed almost the same maximum MR ratio after annealing. This indicates that a smooth or sharp interface has an increased MR ratio. The crystallization temperature of the CoFeB layer showed different dependence on the structure and lattice parameters of the adjacent layer.