| Summary: | 碩士 === 國立中正大學 === 物理學系暨研究所 === 99 === The magnetic properties of ferro-antiferromagnetic (FM/AF) interlayer coupling is investigated by using NiCoO/Co0.10Ni0.90/Cu(001) alloy films. The films were prepared by co-deposition of Ni and Co evaporators in an ultrahigh vacuum chamber with base pressure of 5 x 10-10 mbar. The thickness was monitored by medium energy electron diffraction (MEED), where the peaks of the intensity oscillation indicating a full layer. The composition was adjusted by the deposition rates of Co and Ni individually. The film was then proceeded oxygen exposure to generate the top oxide layers. The structure was resolved by low energy electron diffraction (LEED) and the magnetic property was analyzed by magneto-optical Kerr effect (MOKE).
At 300 K, the magnetization is at the in-plane direction for the films of thickness ranging from 11 to 20 monolayer (ML). Below 180 K, the magnetization vanishes for the film of 11ML. The magnetization coexists at in-plane and out-of-plane of the film for the thickness of 12ML. The magnetization has spin reorientation transition (SRT) for the film of 13ML. For the films above of 15ML, only in-plane magnetization is found with coercivity enhanced. The temperature 180 K is proposed to be the Néel temperature of the top oxide layer. The results might indicate these various magnetic transitions are driven by the formation of the magnetic ordering of the AF oxide layer.
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