We report magnetoresistance measurements on Ni1-xMnx/SiO2/Ni (x = 0.27, 0.28) films with various thickness of SiO2 layer as a function of field and temperature. In the temperature dependence of the magnetoresistance, we observed that the temperature Tf at which the disagreement between field cooled and zero field cooled data appears increased with decreasing thickness of SiO2 layer. Tf was higher than that of Ni73Mn27 film. This result suggests that the spin glass transition temperature Tg increased with decreasing thickness of SiO2 layer. The increase of Tg can be interpreted by magnetic interaction between magnetic moments in NiMn and Ni layers via conduction electrons leaking through the SiO2 layer.
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