Fe/MgF 2/Co magnetic tunnel junctions (MTJs) with an oxide seed layer (MgO, Fe-O) inserted between an Fe bottom electrode and a MgF 2 barrier layer have been prepared through the use of molecular beam epitaxy, and the effects of the seed layers on structure of subsequently deposited MgF 2 barrier layers and tunnel magnetoresistance (TMR) have been investigated. The crystallographic orientation of MgF 2 layers depends significantly on the seed layers, and furthermore, it has been found that the surface roughness of MgF 2 layer is reduced by inserting a MgO seed layer. In Fe/MgF 2 (3-12 nm)/Co MTJs without any seed layer, top Fe and bottom Co electrodes contact each other through pin holes in MgF 2 layers. On the other hand, however, Fe and Co electrodes are separated both magnetically and electrically in Fe/MgO(0.3-0.5nm)/MgF 2 (2-5 nm)/Co MTJs, i.e., MgF 2-based MTJs have successfully been prepared by inserting a thin MgO seed layer, resulting in TMR of about 10% observed at 4.2 K.
ASJC Scopus subject areas
- Physics and Astronomy(all)