Phase Control in Spin-Charge-Photon Coupled Systems

某些固体中的电子由于它们之间的库仑和交换相互作用以及电子-晶格相互作用而具有很强的相关性。该项目的目标是了解由电子相关带来的新相的物理学，并在弱外部刺激触发的这些相之间的相变基础上开辟一个新的电子学领域；其中有光激发。目标材料包括过渡金属氧化物、有机固体和半导体。来自各种技术的实验数据，包括输运、磁和热测量、材料开发、激光光谱学和x射线椭偏仪，一直受到理论小组的不断质疑。为高质量的晶体生长和从太赫兹到紫外线的超快光学光谱建立了强大的技术基础。项目成员之间的协同合作对于发展材料科学领域至关重要，在这个领域中，人们可以在共同的基础上讨论低能输运现象和高能光激发；这是研究强相关电子系统的一个特别相关的方面。我们的发现包括光诱导绝缘体-金属跃迁，超导性与金属-绝缘体跃迁之间的联系，轨道量子（轨道子）和超快光开关。这些结果将是我们建立下一代电子产品的基础。该项目已成为世界范围内强相关电子系统研究的中心。为了在项目终止后加强和扩展我们的活动，2001年4月在东京大学工学院成立了量子相位电子中心。

Electrons in certain solids have strong correlations due to the Coulomb and exchange interactions among them and the electron-lattice interaction. The objective of the Project was to understand the physics of novel phases brought about by the electron correlation and to open up a field of new electronics based on the phase transitions between these phases triggered by weak external stimuli ; among them is photo-excitation. The target materials cover transition metal oxides, organic solids, and semiconductors. Experimental data derived from various techniques including transport, magnetic, and thermal measurements, materials development, laser spectroscopy, and x-ray ellipsometry have been constantly interrogated by the theory group. A strong technical base has been established for high-quality crystal growth and for ultrafast optical spectroscopy ranging from THz to UV. The synergetic collaboration among the Project members have been essential in developing a field of materials science, in which one can discuss the low energy transport phenomena and high energy optical excitation on the common footing ; a particularly relevant aspect for the study of the strongly correlated electron systems. The list of our finding includes the photoinduced insulator-metal transition, the connection between the superconductivity and the metal-insulator transition, the orbital quanta (orbiton), and ultrafast photo-switching. These results will be the basis on which we can establish the electronics for the next generation.The Project has well served as the worldwide center for the study of strongly correlated electron systems. In order to strengthen and extend our activity after the termination of the Project, Quantum-Phase Electronic Center has been established in the School of Engineering, The University of Tokyo in April, 2001.