Bias-voltage controlled resistance in a magnetic tunneling junction with an inserted thin metallic layer

We apply the spin-polarized free-electron model to study the resistance change in a ferromagnet/metal/insulator/ferromagnet magnetic tunneling junction, and find two types of resistance change. One type is varied by the magnetization configuration between two ferromagnetic layers, and the other type is controlled by the polarity of the bias-voltage. The former is the so-called tunneling magnetoresistance, and the latter is named the bias-voltage controlled resistance. Under suitable conditions, we show that both resistance changes resulting from the bias-voltage controlled resistance and the tunneling magnetoresistance are equal in magnitude, and are larger than the resistance change in a conventional ferromagnet/insulator/ferromagnet magnetic tunneling junction.