Articles you may be interested in 80% tunneling magnetoresistance at room temperature for thin Al-O barrier magnetic tunnel junction with CoFeB as free and reference layers J. Appl. Phys. 101, 09B501 (2007) ͑thick-nesses unit in nanometers͒ has been investigated. The tunnel magnetoresistance ͑TMR͒ shows a large increase up to 54.4% after annealing at 265°C due to the improved characteristic properties of the barrier and the interface between the barrier and the ferromagnetic electrodes. The TMR was observed to decrease drastically above the annealing temperature of 310°C accompanied by a notable increase of junction resistance and coercivity of the free layer. The amorphous Co 62 Fe 20 B 18 layers seem to behave as a barrier of diffusion, preventing the migration of Mn or Cu atoms into the interface between the barrier and the ferromagnetic layers. This may cause the drastic decrease of TMR due to the deterioration of the barrier and its interface with Co 62 Fe 20 B 18 layers. The observed crystallization in the amorphous Co 62 Fe 20 B 18 layers is considered to contribute to the increase in coercivity of the free layer.