MRI: Development of a 20-Tesla Spectroscopic Imaging STM for Nanoscale Studies of Complex Electronic/Magnetic Materials

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Technical AbstractSpectroscopic Imaging Scanning Tunneling Microscopy (SI-STM) allows the energy-resolved density-of-electronic-states (essentially the quantum wavefunctions of the electrons) to be imaged with atomic-resolution. This technique is a key tool for development of advanced magnetic/electronic materials: the impact on electron wavefunctions of impurity/dopant atoms, the crystal lattice, electron-electron interactions and external electric/magnetic fields, can all be determined directly at the atomic scale. But many of the most important and revealing phenomena in complex electronic/magnetic materials occur at very high magnetic fields. At Cornell University, we propose to develop the world's first very high magnetic field SI-STM facility - operating with atomic resolution in fields between 0 and 20 Tesla, with tip/sample temperature between 0.25K and 100K. It will then, for the first time, become possible to address crucial scientific challenges in atomic-scale electronic structure at high magnetic fields. These include, for example, quantum hall effects in graphene, field-induced superconductor-insulator transitions in cuprates, colossal magneto-resistance in manganites, possible electronic supersolid phases in cuprates, and field-induced quantum phase transitions in other transition metal oxides. This unprecedented system will operate as a user facility at Cornell, allowing wide access for nanoscale studies of complex electronic/magnetic materials in very high magnetic fields. Furthermore, as recommended by the National Academy, the National High Magnetic Field Lab (NHMF) in Tallahassee needs to achieve such capabilities. Upon completion of the Cornell system, the technology will be transferred NHMFL, bringing high field SI-STM into use for the widest scientific community.Lay AbstractSpectroscopic Imaging Scanning Tunneling Microscopy (SI-STM) is a new technique for imaging directly, the wavefunctions of electrons in complex electronic/magnetic materials. Such materials exhibit, for example, high temperature superconductivity, colossal magneto-resistance and giant thermoelectric power. They will be of profound technological relevance in the future. But many important and revealing phenomena of these complex electronic/magnetic materials occur at high magnetic fields where no SI-STM capabilities exist. To address this deficiency, we propose to develop of the world's first high magnetic field (20 Tesla) SI-STM system. It will operate as a visiting-user facility (also providing advanced training of students/ postdocs) for studies of nanoscale high-field electronic phenomena in a variety of complex electronic/magnetic materials. These will include graphene, cuprates, manganites, ruthenates and other transition metal oxides. Finally, upon completion, the design of the system will be transferred to the Nat. High Magnetic Field Lab. (NHMFL) at Tallahassee, bringing an unprecedented scientific instrument into general use for the widest scientific community at a national facility.