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。当纳米环的尺寸接近单个磁畴的尺度时，铁磁纳米环表现出独特的磁性状态。封闭通量？漩涡？状态存在于适当大小的盘和环中，其中圆形场线完全包含在结构内。该涡旋的手征性已经被提出作为新型存储器设备中的存储位，但是对于均匀的外部场，对手征性的控制已经被证明是具有挑战性的。 这个霍利奥克山学院和马萨诸塞州大学阿默斯特分校的合作项目，通过使电流通过原子力显微镜的尖端，直接探索了涡旋状态的切换。 该电流将产生控制涡旋手性的方位角磁场。 模拟预测，方位角施加的字段结果在有趣的国家以外的旋涡，产生稳定的360度畴壁，和不对称的影响的磁性状态将被检查。 这项工作将涉及霍利奥克山学院的女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，课程材料的磁性将被开发，并与K12教师和附近的斯普林菲尔德技术社区学院的既定方案包括。非技术摘要：这个奖项是根据2009年美国复苏和再投资法案（公法111-5）资助。纳米级磁体具有独特的磁状态，可用作新型数据存储器件。 计算机硬盘驱动器目前存储信息的二进制位？一个？然后呢？0吗？它们被编码在有效的小条形磁铁中，北极或南极指向上。 磁性纳米环提供了一种独特的状态，没有磁极，而是可以存储？一个？然后呢？0吗？顺时针或逆时针方向的磁场，漩涡？状态 这个霍利奥克山学院（MHC）和马萨诸塞州阿默斯特大学（UMass）之间的合作项目，探索磁性纳米环的物理学。 麻省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微小的线定位在纳米环的中心。 通过导线的电流产生一个磁场，允许控制圆形磁化的方向，这是传统技术难以实现的壮举。这项工作将涉及霍利奥克山学院的女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，关于磁性的课程材料将与K12教师和附近的斯普林菲尔德技术社区学院一起开发并纳入既定计划。

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.