Space-charge trap mediated conductance blockade in tunnel junctions with half-metallic electrodes

Feng, J. F.; Kim, T.-H.; Han, X. F.; Zhang, X.-G.; Wang, Y.; Zou, J.; Yu, D. B.; Yan, H.; Li, A. P.
November 2008
Applied Physics Letters;11/10/2008, Vol. 93 Issue 19, p192507
Academic Journal
A conductance blockade effect has been observed in the magnetic tunnel junction consisting of La0.7Sr0.3MnO3 electrodes and a SrTiO3 barrier. The blockade effect is correlated with the space-charge trap states in the barrier. The blockade threshold eVB=128 meV is significantly greater than Coulomb charging energy EC=11 meV. The blockade can be lifted with a magnetic field, accompanied by a very large magnetoresistance up to 10 000%. The intriging blockade behavior is distinctly different from the conventional Coulomb blockade effect, showing a unique spin-dependent tunneling process mediated by the localized charge trap states.


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