2021/10/11 by César González‐Ruano, González-Ruano, César, C. Tiuşan +5 · 1 citation
Physics and Astronomy · Materials Science · #Magnetic properties of thin films #ZnO doping and properties #Copper-based nanomaterials and applications
paper · pdf · doi:10.48550/arxiv.2110.05061
Spin-resolved electron symmetry filtering is a key mechanism behind giant\ntunneling magnetoresistance (TMR) in Fe/MgO/Fe and similar magnetic tunnel\njunctions (MTJs), providing room temperature functionality in modern spin\nelectronics. However, the core process of the electron symmetry filtering\nbreaks down under applied bias, dramatically reducing the TMR above 0.5 V. This\nstrongly hampers the application range of MTJs. To circumvent the problem,\nresonant tunneling between ferromagnetic electrodes through quantum well states\nin thin layers has been used so far. This mechanism, however, is mainly\neffective at low temperatures. Here, a fundamentally different approach is\ndemonstrated, providing a strong TMR boost under applied bias in\nV/MgO/Fe/MgO/Fe/Co hybrids. This pathway uses spin orbit coupling (SOC)\ncontrolled interfacial states in vanadium, which contrary to the V(001) bulk\nstates are allowed to tunnel to Fe(001) at low biases. The experimentally\nobserved strong increase of TMR with bias is modelled using two nonlinear\nresistances in series, with the low bias conductance of the first (V/MgO/Fe)\nelement being boosted by the SOC-controlled interfacial states, while the\nconductance of the second (Fe/MgO/Fe) junctions controlled by the relative\nalignment of the two ferromagnetic layers. These results pave a way to\nunexplored and fundamentally different spintronic device schemes, with\ntunneling magnetoresistance uplifted under applied electric bias.\n