Abstract
We investingate the tunnel magneto-resistance ratio (TMR) of the model that the electron state in the ferromagnetic electrodes is written by the free electron in the exchange magnetic field, and that in the insulating film is written by the tight-binding model. The bias voltage and temperature dependences of TMR for various barrier heights are calculated by employing the Keldysh formalism. The TMR at 0 K decreases in proportion to the bias with decreasing the bias. The TMR at zero bias also decreases with increasing the temperature. The proportion of the decrease is smaller than that with increasing the bias.
