鈷奈米結構的磁性研究

Abstract

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Surface Science influences a wide range for the fundamental researches of chemistry and physics occurring at surfaces and interfaces. Especially for ultrathin films, the effective magnetic anisotropy can be affected by the surface and interfacial conditions because of the large surface-to-volume ratio. On the other hand, because of the potential uses of low-cost and flexible-substrate-based electronics, semiconducting organic materials have attracted much attention. According to the key points of these issues mentioned above, a hybrid interface such as antiferromagnetic/ferromagnetic, organic/ferromagnetic, and electrolyte/ferromagnetic can be more attentive. In this dissertation, five topics are collected in hybrid interfaces under different environments. Although the research topics are studied in different environments such as ultrahigh vacuum, ex-situ measurement, and solution process. The surface science technique is the basic tool in this dissertation. At first, influences of antiferromagnetic grains on exchange bias phenomena in CoO/Co bilayers on a semiconductor surface were investigated. The results provide the insights into our knowledge related to controlling the temperature dependence of exchange bias and related mechanisms. Second, interaction transfer of silicon atoms forming Co silicide for Co/root 3 x root 3 R30 degree-Ag/Si(111) and related magnetic properties provides a possible way of growing flat magnetic layers on silicon substrate with controllable silicide formation. Third, the magnetic properties for single crystal rubrene/Co multilayers is investigated. The rubrene/Co multilayers show unusual magnetization and exchange bias phenomenon in low temperature. Fourth, the electric field modifications on the coercive force for electrochemical etched Co/Pt(111) films are investigated. Variations of the coercive force between 0.31 and 0.38 kOe are reproducible for electrochemical etched Co/Pt(111) under conditions of repeatedly electric potential at -500 and -400 mV. At last, reversible control of coercive force for Co/Pt(111) by varying the electric potential and the related mechanism are investigated. The mechanism is proposed that electric potential tuning the coercive force is related to the thickness of the ferromagnetic layer because of the magnetic anisotropy energy changes. Moreover, the variation of coercive force with higher efficiency for smaller thickness of ferromagnetic layer is observed. All of these topics can improve the applications of magnetic recording media and spintronic devices.