Development of a Cryogenic Scanning Tunneling Microscope for the Study of Atomically-Fabricated Structures in a Variable Magnetic Field

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9503837 Crommie The scanning tunneling microscope (STM) has recently grown from being a tool of surface characterization to a tool of surface modification. The same abilities that allow one to image single atoms can now be used to position them. Little work has been done, however, involving the controllable manipulation of single atoms. The fabrication and characterization of atomic scale structures thus remain a largely untouched scientific frontier. We intend to develop the next generation atomic manipulation device. This will be accomplished through the construction of an ultra-high vacuum (UHV) cryogenic STM. The STM system will be integrated with a UHV surface preparatory facility capable of growing epitaxial metal films. Magnetic fields up to 3 Tesla will be applied to the low temperature sample region using a superconducting magnet. The STM will be used to build nanometer scale structures one atom at a time. These structures will then be studied under ambient conditions, in the presence of a magnetic field, and under the influence of a background transport current. The main objective of this work is to gain a better understandine of the properties of artificial atomic scale structures and the surfaces that support them. The proposed instrument will allow a new type of interactive research in condensed matter physics. Rather than remain passive observers, researchers will be able to take an active role in the microscopic events unfolding before them. The STM will become a new pair of hands with which to shape the atomic landscape. For instance, if it is desired to know the effect of a defect at a particular site on the surface, then the researcher will put a defect at that site. If it is desired to know the property of a particular array of atoms, then the researcher will simply assemble such an array. If the effect of proximity between two chemical species is desired, then the researcher will push the individual reactants clos er together and observe the results. The ability to manipulate matter at so fundamental a level is a significant new capability whose effects are only beginning to be felt. All fields of science concerned with phenomena at the atomic scale should eventually be impacted by these developments.