We demonstrated that a large TMR ratio of 753 % has been observed at 2 K in a MTJ using a Co2MnSi Heusler alloy electrode and a crystalline MgO tunnel barrier. At room temperature (RT), we also have observed a large TMR ratio of 217 %, which value at RT is much larger than that of MTJs using an amorphous Al-oxide tunnel barrier. However, the temperature dependence of the TMR ratio was still large. In order to improve the interface, we investigated the TMR effect in Co2MnSi/CoFeB(0-2 nm)/MgO/CoFe MTJs. TMR ratio was enhanced by inserting a thin CoFeB layer at the Co2MnSi/MgO interface. The MTJ with CoFeB thickness of 0.5 nm exhibited the highest TMR ratio. From the conductance-voltage measurements for the fabricated MTJs, we inferred that the highly spin polarized electron created in Co2MnSi can conserve the polarization through the 0.5 nm thick FeB layer.
ASJC Scopus subject areas
- Materials Science(all)