| Summary: | Based on atomic first principles, we predict enhanced thermal spin transfer (TST) effects and small switching temperature gradient in Fe $| $ MgO $| $ Fe $| $ MgO $| $ Fe double-barrier magnetic tunnel junctions (MTJs). At room temperature, temperature gradient ${\rm{\Delta }}T$ ∼10 ${\rm{K}}$ with ${\rm{\nabla }}T$ ∼10 K nm ^−1 across barriers would be sufficient to switch the magnetic configurations circularly in a junction with 3 MgO atomic layers (L), which is about one order smaller than that in Fe $| $ MgO(3L) $| $ Fe MTJs. This temperature gradient is under the current experimental capability. The resonant quantum-well states in companion with resonant interfacial states are responsible for the enhancement. Moreover, a thermal induced ‘off’ state is found in a double-barrier MTJ.
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