EFFECT OF OXYGEN INCORPORATION ON MAGNETORESISTANCE IN CO/CU MULTILAYERS

The background pressure dependence of magnetoresistance (MR) ratio of Co/Cu multilayer films and the effect of the Fe buffer layer were studied. Secondary ion mass spectrometry (SIMS) measurement of the films and in situ quadrupole mass spectrometry (QMS) analysis in conjunction with background pressure dependence of MR ratio confirmed that the oxidation of Co/Cu gives a crucial influence to the giant magnetoresistance (GMR) effect. The oxidation of Co/Cu weakens the antiferromagnetic coupling, and results in the low MR ratio. The Fe buffer layer absorbs the residual oxygen, and this leads to the increase of the MR ratio. The MR ratio of (Co1 nm/Cu1 nm)100/Fe2.5 n. film deposited under low background pressure and high deposition rate so as to suppress oxidation reached over 80% at RT and 160% at 2 K.