Mesoscopic Spin Mechanics

电子携带电荷、磁矩、质量和机械角动量。磁性和电荷输运之间相互作用的深入研究，或“自旋电子学”，极大地丰富了我们对磁性材料的基本理解，极大地扩展了磁性器件的视野。通过对磁力和机械运动相互作用的详细探索，“自旋力学”也存在类似的机会。***自旋力学在一个世纪前首次被探索。2015年是展示磁学和力学之间内在耦合的重要出版物的百年纪念。巴尼特观察到磁化随旋转的变化，而爱因斯坦与德哈斯合作，测量了相反的情况（在爱因斯坦唯一发表的实验中）。现在正是对这种物理学重新产生兴趣的好时机。这种耦合的时间尺度是磁性的基本特征，从未被测量过。对于较小的结构，如自旋电子学，这种效应的重要性会增加。新的物理学可能会出现，可能包括在信息存储等应用中控制磁性的新方法，这次是利用力学。***这一提议的时机也很关键，因为有机会利用相关技术的巨大进步。芯片上“腔光力学”的发展彻底改变了诱导和检测纳米机械运动的实验能力。与质子直径的一小部分相对应的纳米结构的位移现在可以被测量，纳米机械运动由光学弹簧力强有力地驱动。极快的数字测量电子，新的纳米制造工艺，以及用于数值设计和建模的桌面超级计算，都是过去几年的新能力。纳米力学方法是对现有的先进磁测量方法的补充，并使我们能够解决磁学中的基本问题。这项工作为高素质人才提供了极好的培训机会。8名优秀研究生在本资助期内完成学业，2名博士后获得终身教职。继续工作的成果将使磁性在化学、生物学、地球科学和空间科学中的新的跨学科应用成为可能。

Electrons carry charge, magnetic moment, mass, and mechanical angular momentum. Intensive study of the interplay between magnetism and charge transport, or 'spin electronics', has tremendously enriched our fundamental understanding of magnetic materials and enormously expanded the horizons for magnetic devices. An analogous opportunity exists for 'spin mechanics', by way of detailed exploration of the interactions of magnetism and mechanical motion.***Spin Mechanics first was explored a century ago. 2015 is the centennial of key publications demonstrating the intrinsic coupling between magnetism and mechanics. Barnett observed magnetization changes in response to rotation, and Einstein, working with de Haas, measured the converse (in Einstein's only published experiment). Now is the right time for renewed interest in this physics. The time scale of this coupling is a fundamental characteristic of magnetism and has never been measured. The effects increase in significance for smaller structures, as in the case of spin electronics. New physics can occur, potentially including to new ways of controlling magnetism for applications such as information storage, this time using mechanics.***Also key to the timing of this proposal are opportunities to take advantage of great advances in related, enabling technologies. Experimental capabilities for inducing and detecting nanomechanical motion have been revolutionized by the development of on-chip "cavity optomechanics". Displacement of a nanostructure corresponding to a small fraction of the diameter of a proton can now be measured, and nanomechanical motion powerfully driven by optical spring forces. Extremely fast digital measurement electronics, new nanofabrication processes, and desktop supercomputing for numerical design and modeling, all are new capabilities from just the past couple of years.***The nanomechanical approach is complementary to existing, advanced magnetic measurement methods, and has enabled us already to address fundamental questions in magnetism. The work provides excellent training opportunities for highly qualified personnel. Eight talented graduate students completed their studies during the present granting period, and two postdoctoral fellows went on to tenure-track faculty positions. Outcomes from the continuing work will enable new interdisciplinary applications of magnetism in chemistry, biology, geoscience, and space science.