Search for alternative magnetic tunnel junctions based on all-Heusler stacks

By imposing the constraints of structural compatibility, stability and a large tunneling magneto-resistance, we have identified the Fe$_3$Al/BiF$_3$/Fe$_3$Al stack as a possible alternative to the well-established FeCoB/MgO/FeCoB in the search for a novel materials platform for high-performance magnetic tunnel junctions. Various geometries of the Fe$_3$Al/BiF$_3$/Fe$_3$Al structure have been analyzed, demonstrating that a barrier of less than 2~nm yields a tunneling magneto-resistance in excess of 25,000~\% at low bias, without the need for the electrodes to be half-metallic. Importantly, the presence of a significant spin gap in Fe$_3$Al for states with $\Delta_1$ symmetry along the stack direction makes the TMR very resilient to high voltages

Spin injection and magnetoresistance in MoS2-based tunnel junctions using Fe3Si Heusler alloy electrodes

Recently magnetic tunnel junctions using two-dimensional MoS2 as nonmagnetic spacer have been fabricated, although their magnetoresistance has been reported to be quite low. This may be attributed to the use of permalloy electrodes, injecting current with a relatively small spin polarization. Here we evaluate the performance of MoS2-based tunnel junctions using Fe3Si Heusler alloy electrodes. Density functional theory and the non-equilibrium Green?s function method are used to investigate the spin injection efficiency (SIE) and the magnetoresistance (MR) ratio as a function of the MoS2 thickness. We find a maximum MR of ~300% with a SIE of about 80% for spacers comprising between 3 and 5 MoS2 monolayers. Most importantly, both the SIE and the MR remain robust at finite bias, namely MR?>?100% and SIE?>?50% at 0.7?V. Our proposed materials stack thus demonstrates the possibility of developing a new generation of performing magnetic tunnel junctions with layered two-dimensional compounds as spacer