CAREER: Ultrafast Magnetism in Complex Materials: Coherent and Cooperative Phenomena

* 非技术性 * 现在对基础科学和技术提出的一个主要挑战是在十万亿分之一秒内检测，理解和控制复杂系统中的自旋-纳米磁体的集合。一方面，由相互连接的单个纳米磁性构建块制成的复杂结构可以表现出有价值的特性和改进的功能，这些特性和功能从根本上不同于其组件的总和。另一方面，这样的动态磁过程比迄今为止使用的传统热磁过程快至少1000倍，从而在现代磁光记录工业中具有超过磁切换速度（0.1-10 GHz）的上限的巨大希望，并且能够实现极高速磁存储/逻辑器件。该提案已经确定了通过利用中红外和远红外（每秒万亿次）电磁辐射的超短闪光来解决这些问题的一些主要机会。这项“超快自旋挑战”的成功将揭示先进磁系统中尚未发现的动态过程，并为所发现的问题提供最终解决方案。该提案包括相互关联的具体教育和推广计划，涵盖高中教师及其学生，本科生和研究生水平的学生培训;旨在吸引和留住有才华的学生从事科学职业，并指导他们沿着他们的成功之旅;开发新课程，补充实践实验室模块，强调超快激光技术，再加上本科生和研究生课程。技术 * 本提案利用飞秒激光激发的动态磁光光谱方法，探索纳米级和复杂磁性系统中的超快磁性现象。 当今凝聚态物理和材料科学中最具挑战性的问题之一是，人们是否可以在飞秒时间尺度上检测、理解和控制处于高度非平衡、非热状态的宏观磁序。 这样的过程比迄今为止使用的传统热磁过程快至少1000倍，从而在现代磁光记录工业中具有超过磁切换速度（0.1-10 GHz）的上限的巨大希望，并且能够实现极高速磁存储/逻辑器件。 然而，到目前为止，光激发相干性和/或非热载流子如何能够在这样的时间尺度上实质性地改变宏观有序性，迄今为止还没有得到很好的解决，并且大多数预测的光驱动磁系统的奇异性质还有待观察。这一建议将探索光致非热，fs磁相变，并显着推进我们的知识量子自旋系统驱动远离平衡。该提案包括相互关联的具体教育和推广计划，涵盖高中教师及其学生，本科生和研究生水平的学生培训;开发新课程，补充强调超快激光技术的实践实验室模块。

*** Non-technical ***One major challenge now being posed for fundamental science and technology is to detect, understand and control spins-an ensemble of nanomagnets-in complex systems within one hundred quadrillionth of a second. On one hand, the complex structures made of inter-connected, individual nano-magnetic building blocks can exhibit valuable characteristics and improved functionalities, which are fundamentally different from the sum of their components. On the other hand, such dynamic magnetic processes are at least 1000 times faster than those of the traditional thermal-magnetic processes used thus far, and thereby carry great promise to exceed the upper limit of the magnetic switching speed (0.1-10 GHz) in modern magneto-optical recording industry and enable extremely high-speed magnetic storage/logic devices. This proposal has identified some major opportunities to address these problems via exploiting ultrashort flashes of mid-infrared and far-infrared (trillion cycles per second) electromagnetic radiation. Success in this "ultrafast spin challenge" will reveal as-yet-undiscovered dynamic processes in advanced magnetic systems, and offer ultimate solution towards the problems indentified. The proposal consists of interconnected, specific plans for education and outreach that span high school teachers and their students, undergraduate and graduate level student training; seeks to attract and keep talented students in careers in sciences, and mentor them along their journey to success; develop new courses with complementary hands-on laboratory modules emphasizing ultrafast laser technology, coupled to undergraduate and graduate curriculum.*** Technical ***This proposal explores ultrafast magnetic phenomena in nanoscale and complex magnetic systems using dynamic magneto-optical spectroscopic methods exploiting femtosecond laser excitations. One of the most challenging questions in condensed matter physics and materials science today is whether one can detect, understand and control macroscopic magnetic orders in their highly non-equilibrium, non-thermal states at femtosecond time scales. Such processes are at least 1000 times faster than those of the traditional thermal-magnetic processes used thus far, and thereby carry great promise to exceed the upper limit of the magnetic switching speed (0.1-10 GHz) in modern magneto-optical recording industry and enable extremely high-speed magnetic storage/logic devices. However, thus far how photoexcited coherence and/or non-thermal carriers can substantially modify the macroscopic ordering at such time scales has been poorly addressed to date and most of the predicted exotic properties of photo-driven magnetic systems have yet to be observed. This proposal will explore photoinduced non-thermal, fs magnetic phase transition and significantly advance our knowledge of quantum spin systems driven far from the equilibrium. The proposal consists of interconnected, specific plans for education and outreach that span high school teachers and their students, undergraduate and graduate level student training; develop new courses with complementary hands-on laboratory modules emphasizing ultrafast laser technology.