Collaborative Proposal: Physics of Ferromagnetic Nanorings in an External Azimuthal Field

技术摘要：该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)资助的。当尺寸接近单个磁畴的规模时，铁磁纳米环显示出独特的磁性状态。闭合通量？漩涡？态存在于大小适中的圆盘和环中，其中圆形场线完全包含在结构内。这种旋涡的手性已被提出作为一种新型存储器件的存储比特，但事实证明，在均匀的外场下，对手性的控制具有挑战性。曼荷莲学院和马萨诸塞大学阿默斯特分校的这项合作项目，通过让电流通过原子力显微镜的尖端，直接探索涡旋状态的转换。这种电流将产生一个方位向磁场来控制涡旋的手性。模拟预测，方位向外加磁场会在涡旋之外产生有趣的状态，产生稳定的360度磁场壁，并且不对称性对磁态的影响将被考察。这项工作将涉及芒特霍利奥克学院的本科生以及博士后和研究生，促进两个机构之间的频繁互动。此外，将与K12教师和附近的斯普林菲尔德技术社区学院一起开发磁性课程材料，并将其纳入既定计划。非技术摘要：该奖项由2009年美国复苏和再投资法案(公法111-5)资助。纳米级磁体表现出独特的磁性状态，可用作新型数据存储设备。计算机硬盘驱动器目前以？1？二进制位存储信息。然后呢？0？它们被编码在有效的小条形磁铁中，北极或南极指向上方。磁性纳米环提供了一种没有极点的独特状态，但可以存储？1？然后呢？0？如顺时针或逆时针方向的磁场，即所谓的涡旋？州政府。这个由曼荷莲学院(MHC)和马萨诸塞大学阿默斯特分校(UMA)合作的项目探索了磁性纳米环的物理学。马萨诸塞州大学的制造设施和专业知识将用于制造纳米环。MHC的原子力显微镜能够精确地将一根细丝定位在纳米环的中心。通过导线传递电流会产生磁场，从而可以控制圆形磁化的方向，这是传统技术很难完成的壮举。这项工作将涉及芒特霍利奥克学院的本科生以及博士后和研究生，促进两个机构之间的频繁互动。此外，还将与K12教师和附近的斯普林菲尔德技术社区学院一起开发有关磁性的课程材料，并将其纳入既定的计划中。

Technical Abstract:This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Ferromagnetic nanorings exhibit unique magnetic states as the dimensions approach the scale of a single magnetic domain. The closed-flux ?vortex? state exists in appropriately sized disks and rings, in which the circular field lines are entirely contained within the structure. The chirality of this vortex has been proposed as the storage bit in a novel memory device, but control over the chirality has proven challenging with uniform external fields. This collaborative project between Mount Holyoke College and the University of Massachusetts, Amherst, directly explores the switching of the vortex state by passing a current through the tip of an atomic force microscope. This current will produce an azimuthal magnetic field that controls the vortex chirality. Simulations predict that azimuthally applied fields result in interesting states beyond the vortex, generating stable 360 degree domain walls, and effects of asymmetry on the magnetic states will be examined. This work will involve the undergraduate women at Mount Holyoke College, as well as post-docs and graduate students, fostering frequent interaction between the two institutions. Furthermore, curricular material on magnetism will be developed and included in established programs with K12 teachers and the nearby Springfield Technical Community College.Non-technical Abstract:This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Nanoscale magnets exhibit unique magnetic states that can be used as novel data storage devices. Computer hard drives presently store information in binary bits of ?1? and ?0? that are encoded in what are effectively little bar magnets with either the north or south pole pointing up. Magnetic nanorings offer a unique state that has no poles, but instead could store the ?1? and ?0? as clockwise or counterclockwise magnetic fields in what is called the ?vortex? state. This collaborative project between Mount Holyoke College (MHC) and the University of Massachusetts, Amherst (UMass), explores the physics of magnetic nanorings. The fabrication facilities and expertise at UMass will be used to make the nanorings. The atomic force microscope at MHC is capable of precisely positioning a tiny wire at the center of a nanoring. Passing a current through the wire creates a magnetic field that allows control over the direction of the circular magnetization, a feat that is difficult to accomplish with traditional techniques. This work will involve the undergraduate women at Mount Holyoke College, as well as post-docs and graduate students, fostering frequent interaction between the two institutions. Furthermore, curricular material on magnetism will be developed and included in established programs with K12 teachers and the nearby Springfield Technical Community College.