Inverse magnetoresistance in magnetic tunnel junction with an Fe3O4 electrode

This study shows inverse MR in a NiFe/AlOx/ Fe₃O₄ tunnel junction if sufficiently pure Fe₃O₄ at the interface with the tunnel barrier can be achieved. Magnetic tunnel junction with the structure of Ta 3 nm/Cu 50 nm/Ta 3 nm/NiFe 10 nm/AlOx 2 nm/Fe (1.8 ∼ 10 nm)-oxidation/Fe 5 nm/Ta 3 nm is deposited on oxidized silicon substrates by using an RF/DC sputtering system. Oxidation of the Fe layer is found to result to an inverse MR. As the unoxidized Fe layer decreases, MR also decreases until it reaches zero, that is, the unoxidized residual Fe phase coexist with the Fe₃O₄ phase. As the thickness decrease further to 1.8 nm, the MR curve becomes negative (inverse MR).