Influence of barrier overoxidation and annealing on the inelastic spin-dependent tunneling in AlOx-based junctions T. Dimopoulos, Y. Henry, V. Da Costa, C. Tiusan, and K. Ounadjela JOURNAL OF APPLIED PHYSICS 95, 6936 (2004)
The present work reports on the inelastic, spin-dependent tunneling in magnetic junctions with AlOx barrier and Co50Fe50 ferromagnetic electrodes. The identification of the transport inelastic channels is possible through their distinctive temperature dependencies. For the observed
temperature behavior of the magnetotransport properties of the junctions, two spin-dependent, inelastic mechanisms are proposed: assisted tunneling due to interfacial (a) magnons and (b)
metallic phonons. Their relative contributions are closely linked to the microstructural properties of the ferromagnetic metal/oxide interfaces, related to the plasma oxidation of the tunnel barrier and to thermal annealing.
High resolution transmission electron microscopy images of the as-deposited multilayers, focusing on the AlOx barrier.
Tunnel magneto-resistance loops at 6 K and 290 K for a junction (a) as-deposited and (b) after annealing. The insets zoom in the field region where the antiparallel (high resistance) state of the junction is defined.
Temperature dependence of (a) the conductance in the antiparallel state, (b) the conductance in the parallel state, and (c) the difference in the conductance of the two states. All the quantities are normalized to their value at T=6 K. The bias voltage was set to 5 mV for all of the measurements.
Fitting of the experimental data for an annealed MTJ1 junction,
with the model that takes into account magnons and phonons of the ferromagnetic electrodes.