Over 70% tunneling magnetoresistance at room temperature for a CoFe and AlOx based magnetic tunnel junction

More than 70% tunneling magnetoresistance (TMR) ratio has been observed at room temperature for a CoFe and AlOx based magnetic tunnel junction. The annealing of the epitaxial bottom electrode, Si (001)/Ag fcc (200)∕Co84Fe16 bcc (200), at 400°C prior to fabricating the tunnel barrier and the upper electrode is crucial for achieving this high TMR ratio. Moreover a high output voltage could be obtained for this magnetic tunnel junction due to its high V1∕2, the bias voltage at which the TMR ratio is reduced to half of that near the zero bias. The rationale for obtaining this high TMR ratio is discussed, and there are reasons to believe that the TMR ratio for this junction could be further improved.