Temperature and bias dependence of dynamic conductance - low resistive magnetic tunnel junctions

I-V curves of magnetic tunnel junctions were measured in a temperature range of 5-305 K. Effective barrier parameters were estimated by fitting the dynamical conductance G(V) with the Brinkman-Dynes-Rowell model and fitting the temperature dependence of zero-bias conductance G(T) with the Stratton model. A large discrepancy was discovered when comparing barrier parameters predicted by the two models. The inconsistency between the models can be explained by the presence of an inelastic, spin-independent conductance that is strongly dependent on both temperature and voltage as described by Glazman-Matveev theory of electron hopping. This additional hopping conductance helps explain the observed temperature dependence and bias dependence of magnetic tunnel junction conductance. (C) 2004 American Institute of Physics.