Magnetic Transport Study in NiFe-Al-NiFe Double-tunnel Junctions

Spintronics, which utilizes spin-dependent transport mechanism, is a potential candidate for the next generation electronic devices. Separation of spin transport from charge transport is an essential issue in this emerging field. In this work, we study spin transport behavior in double-barrier tunnel junction structures in which the center electrode is made of Al and the two electrodes are made of Ni₈₀Fe₂₀. One method, which is called spin-valve effect, utilizes two ferromagnetic electrodes composed of parallel or antiparallel magnetization alignments to control transports of spin-polarized current. In antiparallel magnetization alignment, majority spin-polarized current is suppressed by the spin-valve effect and spin polarized electron is accumulated in the central island. If the central island is made of superconductor, the resultant nonequilibrium spin density strongly suppresses the superconductivity. In this study, we investigate the magnetic transport influenced by spin imbalance in NiFe-Al-NiFe double tunnel junctions.