A thermally compensated tube scanner scanning tunneling microscope (STM) has been constructed and successfully tested. This design utilizes two concentric piezoelectric tubes, one for scanning and one for thermal compensation and inertial sample translation (over several mm), as well as fine adjustment of sample position while in tunneling range. This design eliminates the need for mechanical components such as springs, levers, gears, or stepper motors that are known to result in considerable vibration sensitivity, thermal drift, and low-resonance frequencies. This new design demonstrates continuously variable-temperature operation as well as atomic resolution without vibration isolation for the first time in a STM. Thermal drift of less than 1 Å/h and less than 10 Å/K have been determined. Also, the lowest mechanical resonance frequency of 21 kHz makes this new design suitable for high-speed applications such as video rate scanning.

A theoretical model is developed to describe the polarization and depinning of charge-density waves (CDW s) in the inorganic linear-chain compounds which exhibit Frohlich sliding conduction. Each individual impurity within the crystal is assumed to pin the CDW phase very strongly at the impurity site, and dc CDW motion is made possible only by phase slip. Simple estimates are obtained for most observed properties of sliding CDW systems with use of a three-dimensional Ginzburg-Landau analysis. These predictions are found to be in excellent quantitative agreement with available experimental data characterizing virtually every aspect of CDW dynamics.

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