The electronic structure and related physical properties of correlated electron systems

强相关电子系统展示了一些最有趣的物理特性，这些特性对电子设备、可持续能源、生物医学设备、交通运输甚至量子计算的当前和未来应用都很重要。由过渡金属和稀土化合物制成的材料，如它们的氧化物，通常表现出极端的特性，如高温超导性、高热电功率、高介电常数、巨大的磁电阻等等。这些材料不同于传统的半导体，如硅或简单的金属，如铝，其中电子在原子之间移动的电荷在决定应用中起着重要作用。过渡金属氧化物通常是电绝缘体和磁性的，因为电子之间的相互排斥作用很强。然而，化学取代可以将这种磁性绝缘体转变为高温超导体（诺贝尔奖1988），并导致其性质的其他戏剧性变化。支配它们行为的基本物理学仍然是现代科学研究中最大的智力挑战之一。这里，自旋和轨道自由度以及它们与电子的电荷自由度的相互作用起着至关重要的作用。随着原子沉积法制备新型氧化材料的发展，基于界面的全新材料和性能得到了展示，为材料科学和器件应用开辟了新的方向。我们将利用我们在UBC和加拿大光源开发的新的实验设备进行共振X射线散射和原子间原位材料制备，并将这些与新的理论见解一起应用于研究表面，工程界面和战略性选择的过渡金属氧化物的纳米结构。这种新设备特别适合研究埋藏界面的电子结构，这些界面很难或不可能用其他方法以非破坏性的方式进入。在这种界面上发现的惊人特性有望为下一代电子设备形成一个全新的平台。

Strongly correlated electron systems exhibit some of the most interesting physical properties important for present and future applications in electronic devices, sustainable energy, biomedical devices, transportation and perhaps even quantum computing. Materials made of transition metal and rare earth compounds such as their oxides are examples often exhibiting extreme properties such as high temperature superconductivity, high thermoelectric power, high dielectric constants, colossal magneto resistance and many more. These materials are different from conventional semiconductors like Si or simple metals like Al in which the charge of the electrons moving in amongst atoms plays the important role in determining the applications. Transition metal oxides often are electrical insulators and magnetic because of the strong repulsive interaction between the electrons. However chemical substitution can turn such magnetic insulators into high temperature superconductors (Nobel Prize 1988) and cause other dramatic changes in their properties. The basic physics governing their behaviour remains one of the biggest intellectual challenges of modern scientific research. Here the spin and orbital degrees of freedom and their interplay with the charge degrees of freedom of electrons play essential roles. With the recent development of the physical preparation of new oxide materials using an atom by atom deposition approach completely new materials and properties based on interfaces have been demonstrated opening up a new direction in material science and device applications. We will utilize the new experimental facilities we developed at UBC and the Canadian Light source for resonant X ray scattering and in situ atom by atom material preparation and apply these together with new theoretical insights to the study of surfaces, engineered interfaces and nanostructures of strategically selected transition metal oxides. This new facility is especially suited to study the electronic structure of buried interfaces which are hard or impossible to access in a non destructive manner with other methods. The spectacular properties found at such interfaces are predicted to potentially form a whole new platform for the next generation of electronic devices.