磁力显微镜MFM-浙江大学光电科学与工程学院.PPT

AFM 图像 EFM图像 40/89 Electrostatic Force Microscopy (EFM) uses a combination of TappingMode?, LiftMode? and a conductive tip to gather information about the electric ?eld above a sample. Each line of the sample is ?rst scanned in TappingMode operation to obtain the sample topography. The topographic information is stored and retraced with a user- selectable height offset in LiftMode, during which the electrical data is collected. Typical lift heights in EFM range from 20-80 nm. 静电力显微镜(EFM)实例 磁性微探针。探测记录样品表面的磁分布。如磁盘、磁带。 10.5 磁力显微镜(MFM) The AFM operated in the non-contact mode with a magnetic cantilever detects a force gradient (F) containing information from both the surface structure and surface magnetization. F = Fsurface+Fmagnetic Signals from surface topography dominate at close distances to the surface while, at greater distances from the surface (typically beyond 100 nm), the magnetic signal dominates. Consequently, depending on the distance between the surface and the tip, normal MFM images may contain a combination of topography and magnetic signals. Though it is useful to topographically locate where the magnetic domains are, sometimes it is more advantageous to completely separate the two signals from each other. F = Fsurface+Fmagnetic Magnetic force microscopy ? Local magnetic properties ? AFM + tip covered by a layer of ferromagnetic material with specific magnetization 材 料：单晶硅 形 状：圆锥形 针尖高度：7 ?m 针尖曲率：10 nm 圆 锥 角：10? Tip preparation of MFM（a） A typical example is shown in the picture. A carbon contamination needle is grown on top of the pyramidal tip of a commercial Si3N4 AFM cantilever. The needle is covered afterwards from one side with a thermally evaporated 15 nm thick Co80Ni20 film to make it sensitive for MFM mea- surement. Orientation of the needle is chosen to be approximately 10o with respect to the can- tilever plane. Tip preparation of MFM