In accordance with a method of producing an MR (MagnetoResistive) device including
a ferromagnetic tunnel junction made up of a first ferromagnetic layer, an insulation
layer formed on the first ferromagnetic layer and a second ferromagnetic layer
formed on the insulation layer, a metal or a semiconductor is deposited on the
first ferromagnetic layer. The metal or the semiconductor is then caused to react
to oxygen of a ground level to become an oxide layer, which is the oxide of the
metal or that of the semiconductor. Subsequently, the oxide layer is caused to
react to oxygen of an excitation level to form the insulation layer. The second
ferromagnetic layer is formed on the insulation layer.
