Spin-polarized scanning tunneling microscopic study of cobalt cluster on HOPG : from instrumentation to real time measurement



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This dissertation is divided into three parts. The first part provides the introduction and the principles of traditional scanning tunneling microscopy, and then extends the content to the fundamental operation of the spin-polarized variant. The core part describes our home-made sp-STM system in detail, which includes information about the hardware, electronics, and sample/tip preparation. The third part intends to demonstrate the experimental difficulties encountered in doing spin-polarized measurements. We first discuss the elimination of the unpolarized electronic contribution to the overall spectroscopic information on cobalt clusters on graphite (HOPG) system at the nanometer-scale, and then show the possible factors that hinder the atomic-level magnetic study of the spin polarized STM measurement. Preliminary STS analysis of the sample surface is included in the last section.