Spin-Polarized STM is something that I have an interest in because of the possible applications for studies of magnetic nanostructures. It's a very exciting extension of the STM technique that could allow magnetically sensitive microscopy to extend into sub-nm resolution. The ability to observe magnetism on the level of groups of atoms and individual atoms is a very exciting goal from the fundamental research point of view. In practice, the ability to image nanometer scale magnetic structures becomes important as individual bits in magetic storage (e.g. hard drives) become smaller in order to achieve higher recording densities.

Spin-Polarized Scanning Tunneling Microscopy

D. Y. Petrovykh
Physics Department, University of Wisconsin - Madison

Scanning-probe microscopies revolutionized surface science research, providing the possibility of direct observation and manipulation of atomic structure of surfaces with sub-nm precision. Can this awesome power be extended into studies of magnetic properties? Spin-polarized scanning tunneling microscopy proposes to use spin-dependent tunneling to do just that. Here details and preliminary results are reviewed for the two currently developed approaches: magnetic (metallic) tips and optically pumped GaAs tips. Each of the two techniques is beneficial for a specific class of measurements and may ultimately achieve atomic resolution.

This was written as a "review" paper for a physics presentation class. Even in this relatively new field a comprehensive survey would be beyond the scope of the project, so my review is intented as a look at advances in the main approaches to SPSTM. Since I wrote this review in 1997 there have been of course interesting developments in the spin-polarized and magnetic microscopy. The information in the review thus is not the most current anymore, but the work discussed represents important milestones on the quest for SPSTM with atomic resolution.

I am thrilled to tell you that shortly after I've finished my paper, a Spin-Polarized STM review came out as part of "Scanning Probe Microscopy - Analytical Methods" book (Springer NanoScience and Technology series) edited by Prof. Roland Wiesendanger. So after you are done reading about my prospective on the SPSTM's future, you may want to check what one of the experts has to say.

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