金属-非金属ナノグラニュラー膜のMR特性の磁界感度の向上  [in Japanese] Enhancing the Low-Field-Magnetoresistive Response in Metal-Nonmetal Granular Films  [in Japanese]

The low-field-magnetoresistive (MR) response of the tunnel-type magnetoresistance (TMR) of metalnonmetal granular film was examined. The MR ratio at 500 Oe of (Fe_<75>Al_<25>)-0 films prepared by a tandem deposition method increases with increasing Fe grain size and begins to decrease at more than 2.0 nm. This suggests that there is a limit to the improvement in the MR that can be obtained by controlling the film structure. On the other hand, the magnetoresistance of GIG (nano-Granular In Gap) film consisting of soft magnetic and granular TMR films exhibits a huge field response in a low magnetic field. The MR ratio of GIG film consisting of a-C0_<77>Fe_5Si_9B_9 and Co_<39>Y_<14>O_<47> films at 2.5 Oe is more than 2.4%, which is about 250 times larger than that of a Co_<39>Y_<14>O_<47> single-layered film. GIG film consisting of a-C0_<77>Fe_5Si_9B_9 film shows a larger response of the magnetoresistance in a low magnetic field than GIG film consisting of Fe_<66>Ni_<34> film, because the coercivity of a-C0_<77>Fe_5Si_9B_9 film is lower than that of Fe_<66>Ni_<34> film.