Effect of oxygen vacancies on interlayer exchange coupling in Fe/MgO/Fe tunnel junctions

Antiferromagnetic interlayer exchange coupling between Fe3O4 layers across a nonmagnetic MgO dielectric layer

“…More recently, an ab initio electronic structure method has been used to investigate barrier vacancy mediated IEC in Fe/ MgO / Fe junctions. 18 The authors advocate vacancies in the barrier as the origin of AF IEC observed in Fe/ MgO / Fe junctions. However, a large concentration of vacancies in these calculations is not supported by experimental results.…”

MgO thickness-induced spin reorientation transition in Co0.9Fe0.1/MgO/Co0.9Fe0.1 structure

“…Moreover, it was shown that oxygen vacancies, as well as interfacial oxygen, cause the IEC to be antiferromagnetic for MgO thickness below 0.8 nm. [29,30] Indeed, accomplished FMR experiments show the continuous falloff of the intensity of the resonance line of the F B layer as the thickness of MgO is reduced below 1 nm. This observation, in turn, suggests that the magnetic moments on the surface are progressively affected by the interlayer interactions and as a result, the surface anisotropy energy and, consequently, the MAE, changes.…”

Defect-Mediated Properties of Magnetic Tunnel Junctions

“…In both cases large coupling strength is observed comparable to that of metallic spacers. Also, a model for a defect-free Fe-MgO-Fe predicts IEC to be FM at thickness less than 10 [22], [23]. Thus, experimental results differ from theoretical prediction both in magnitude and sign of the coupling.…”

“…The barrier is represented by a rectangular potential of height in which a function located in the barrier at position represents the defect. This potential creates a quantum well containing an impurity level of energy [22], [23]. Fig.…”

“…The experimental results significantly differ from the theoretical predictions for ideal MTJs both in the magnitude and the sign of IEC. The presence of impurities or defects in the barrier may significantly influence IEC [22], [23].…”