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arXiv · 1604.01364

Gap state charge induced spin-dependent negative differential resistance in tunnel junctions

Jun Jiang·X. -G. Zhang·X. F. Han
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Abstract

We propose and demonstrate through first-principles calculation a new spin-dependent negative differential resistance (NDR) mechanism in magnetic tunnel junctions (MTJ) with cubic cation disordered crystals (CCDC) AlO$_x$ or Mg$_{1-x}$Al$_x$O as barrier materials. The CCDC is a class of insulators whose band gap can be changed by cation doping. The gap becomes arched in an ultrathin layer due to the space charge formed from metal-induced gap states. With an appropriate combination of an arched gap and a bias voltage, NDR can be produced in either spin channel. This mechanism is applicable to 2D and 3D ultrathin junctions with a sufficiently small band gap that forms a large space charge. It provides a new way of controlling the spin-dependent transport in spintronic devices by an electric field. A generalized Simmons formula for tunneling current through junction with an arched gap is derived to show the general conditions under which ultrathin junctions may exhibit NDR.

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Jun Jiang, X. -G. Zhang, X. F. Han. 2016-04-05. Gap state charge induced spin-dependent negative differential resistance in tunnel junctions. https://doi.org/10.1209/0295-5075/114/17005

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