  Spin-resolved electron symmetry filtering is a key mechanism behind giant
tunneling magnetoresistance (TMR) in Fe/MgO/Fe and similar magnetic tunnel
junctions (MTJs), providing room temperature functionality in modern spin
electronics. However, the core process of the electron symmetry filtering
breaks down under applied bias, dramatically reducing the TMR above 0.5 V. This
strongly hampers the application range of MTJs. To circumvent the problem,
resonant tunneling between ferromagnetic electrodes through quantum well states
in thin layers has been used so far. This mechanism, however, is mainly
effective at low temperatures. Here, a fundamentally different approach is
demonstrated, providing a strong TMR boost under applied bias in
V/MgO/Fe/MgO/Fe/Co hybrids. This pathway uses spin orbit coupling (SOC)
controlled interfacial states in vanadium, which contrary to the V(001) bulk
states are allowed to tunnel to Fe(001) at low biases. The experimentally
observed strong increase of TMR with bias is modelled using two nonlinear
resistances in series, with the low bias conductance of the first (V/MgO/Fe)
element being boosted by the SOC-controlled interfacial states, while the
conductance of the second (Fe/MgO/Fe) junctions controlled by the relative
alignment of the two ferromagnetic layers. These results pave a way to
unexplored and fundamentally different spintronic device schemes, with
tunneling magnetoresistance uplifted under applied electric bias.
