A unique scanning tunneling microscope (STM) system that operates at ultra-low temperatures (<50 mK), at high magnetic fields (up to 11 T) and in ultra-high vacuum (<10-10 torr) will be developed in this project. An instrument that combines a powerful custom-built dilution refrigerator/magnet system, two UHV chambers for sample transfer and preparation, and a home-built high-resolution STM will be constructed. The ultra-low temperature STM (ULTSTM) instrument will be housed in a state-of-the-art facility inside double-walled acoustic and rf-shielded enclosures, which are constructed on a massive floating floor. The noise reduction resulting from the combination of acoustic, rf, and vibration isolation in this advanced facility will guarantee an unprecedented performance for the ULTSTM system. Femtometer tip stability and microvolt-energy-resolution spectroscopy will be possible with this unique instrument" a combination that opens up the possibility to access important quantum phenomena in a variety of nanoscale systems and complex materials. This instrument will contribute to diverse research activities in the study of quantum phenomena in materials, from the study of unconventional superconductors and quantum phase transitions to the study of quantum entanglement in spin assemblies. The graduate students and undergraduate students involved in this research project will learn state-of-the-art scanning probe microscopy techniques and nanofabrication methods that are of strong interest to both industry and academia.
Microscopes have been pivotal in opening new frontiers in science. Scanning probe microscopes (SPMs) are a new generation of powerful microscopes that operate by mapping on the microscopic scale the local interaction between a pointed probe and the sample. These novel instruments have taken the ability to image matter to the atomic scale and have opened fresh perspectives on everything from semiconductors to biomolecules. The proposed project will develop a unique scanning tunneling microscope (STM) that advances the frontiers of measurement to ultra-low temperatures where important electronic phenomena occur. Unusual states of matter or quantum coherent processes are extremely sensitive to thermal agitation; hence, they are only observable at temperatures close to absolute zero. The new instrument will make it possible to obtain unprecedented details of quantum behavior by mapping electronic waves in materials with sub-Angstrom resolution. The researchers will be more than just passive observers, as the proposed instrument allows them to tailor the atomic landscape by manipulating matter one atom a time. This fine control over matter will be used to perform unprecedented experiments that scrutinize our current theoretical understanding of electronic phenomena in matter. The students participating in this project will learn to design sophisticated scientific instrumentation and use them to attack some of the most challenging problems in physics of materials.
