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

技术摘要光谱成像扫描隧道显微镜(SI-STM)使能量分辨的电子态密度(实质上是电子的量子波函数)能够以原子分辨率成像。这项技术是开发先进的磁性/电子材料的关键工具：杂质/掺杂原子、晶格、电子-电子相互作用和外部电场/磁场对电子波函数的影响都可以在原子尺度上直接确定。但在复杂的电子/磁性材料中，许多最重要和最具启发性的现象都发生在非常高的磁场中。在康奈尔大学，我们计划开发世界上第一个非常高磁场的SI-STM设备-在0到20特斯拉的场中以原子分辨率运行，针尖/样品温度在0.25K到100K之间。到那时，它将首次有可能在强磁场下解决原子级电子结构中的关键科学挑战。例如，石墨烯中的量子霍尔效应，铜酸盐中的场致超导体-绝缘体转变，锰氧化物中的巨大磁阻，铜酸盐中可能的电子超固态相，以及其他过渡金属氧化物中的场致量子相变。这一史无前例的系统将作为康奈尔大学的用户设施运行，允许在非常高的磁场中对复杂的电子/磁性材料进行纳米级的研究。此外，根据国家科学院的建议，塔拉哈西的国家强磁场实验室(NHMF)需要实现这种能力。康奈尔系统建成后，这项技术将转移到NHMFL，使高场SI-STM应用于最广泛的科学界。光谱成像扫描隧道显微镜(SI-STM)是一种直接成像复杂电子/磁性材料中电子波函数的新技术。例如，这种材料表现出高温超导、巨大的磁阻和巨大的温差电势。它们将在未来具有深远的技术相关性。但是，这些复杂的电子/磁性材料的许多重要的和揭示的现象发生在没有SI-STM能力的强磁场中。为了解决这一不足，我们建议开发世界上第一个强磁场(20特斯拉)SI-STM系统。它将作为访问用户设施(还为学生/博士后提供高级培训)，研究各种复杂电子/磁性材料中的纳米级高场电子现象。这些将包括石墨烯、铜酸盐、锰氧化物、Ruthenate和其他过渡金属氧化物。最后，完成后，系统的设计将移交给NAT。强磁场实验室。在塔拉哈西(NHMFL)，一种史无前例的科学仪器在国家设施中为最广泛的科学界普遍使用。

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.