Giant tunneling magnetoresistance with electron beam evaporated MgO barrier and CoFeB electrodes

Abstract

Electron-beam (EB) evaporated MgO grows with (001) texture on amorphous CoFeB when the deposition rate is kept below 5 pm/s. Magnetic tunnel junctions (MTJs) fabricated using this method exhibit similar to 240% magnetoresistance at room temperature for a 2.5 nm thick EB-MgO barrier, which is similar to the value for a radio frequency (rf) sputtered barrier with the same junction geometry. The average barrier height of the EB-MgO is 0.48 eV, which is higher than previously reported values for rf-MgO barriers and it increases with increasing annealing temperature. Our results show that EB-MgO could be a simpler alternative to rf-MgO in MTJs without any compromise in the tunnelling magnetoresistance.