RUI: Core Size Effects on Flux-Flow Resistivity: Collaborative Project to Launch a Program Exploring Flux Dynamics in Weak-Pinning Systems

摘要，非技术：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。美国迫切需要对其老化的电网进行现代化改造，2003年8月美国东北部大范围停电事件突显了这一事实。此外，目前电网中使用的导电材料向环境释放废热，每年有价值数十亿美元的电力从未到达用户手中。这是由于传统导体中的耗散电阻。另一方面，超导体以零损耗导电。因此，美国和世界各地的科学家和工程师都在积极开发用于电网现代化的超导线路，这使得对超导化合物电磁特性的理解成为主要的研究重点。其中，一套关键的机制是磁场如何在各种条件下穿透技术相关超导体的内部。这种穿透以涡旋的形式发生。磁通量的离散量子也会相互作用。这些涡流的运动极大地影响了超导体的载流能力；因此，涡旋动力学的性质得到了广泛的研究。本项目的兴趣在于这些漩涡的内部结构或核心如何影响它们的自由运动？一些很少被研究的东西，因为自由运动是在技术上具有挑战性的条件下实现的，只有这个小组和少数其他人实现了。该项目也被设计为由本科生管理，从而为他们从事科学事业做好准备。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。磁通量量子（也称为涡流、通量线或通量子）的动力学？外部磁场开始穿透与技术相关的II型超导体的内部？继续成为理解和应用这些材料的研究重点，尤其是高温铜酸盐。各个小组正在探索的一个特殊方面是这些通量量子的非超导核心的性质，它仍然没有完全理解，但已经知道会影响通量量子之间的相互作用，从而影响相变的性质？通量重要吗?在各种条件下。磁通磁芯很少被研究的一个方面是，本项目特别准备探索磁通磁芯对磁通流电阻率的场依赖性的影响，这是与自由磁通流（FFF）相相关的直流驱动耗散，这是一个高度有序的动态相，其中磁通物质的弹性克服了引起无序的钉住和热波动。补充直流输运测量是磁化，热容，和核磁共振在相同的样品？通过现在和未来的合作。所有这些都将在至少四种不同材料的高质量晶体上进行，以探索化合物依赖的微妙之处。最终目标是提供一个独特的全面的观点，以了解磁通芯的性质。该项目还旨在为物理学本科生提供研究经验，为研究生及以后的学习做准备；因此，学生要积极参与。

Abstract, non-technical:This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The US is in dire need to modernize its aging electric power grid, a fact underscored recently by the widespread power outage in the Northeast in August 2003. Also, the conducting materials used in the present grid release waste heat to the environment, worth billions of dollars annually in electricity that never reaches its users. This is due to the dissipative resistance in conventional conductors. Superconductors, on the other hand, conduct electricity with zero dissipation. Thus, scientists and engineers throughout the US and around the world are actively developing superconducting lines for grid modernization, which has made the understanding of the electromagnetic properties of superconducting compounds a major research priority. Of these, one critical set of mechanisms is in how magnetic fields penetrate the interior of technologically relevant superconductors under various conditions. Such penetration occurs in the form of vortices ? discrete quanta of magnetic flux which also interact with each other. The motion of these vortices greatly affects the current-carrying capability of superconductors; thus the nature of vortex dynamics has been widely investigated. The interest in the present project is in how the internal structure or cores of these vortices affect their free motion ? something rarely studied, since free motion is achieved under technically challenging conditions achieved only by this group and few others. The project is also designed to be run by undergraduate students, thus preparing them for careers in science.Abstract, technical:This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The dynamics of magnetic flux quanta (also known as vortices, flux lines, or fluxons) ? by which an external magnetic field begins to penetrate the interior of technologically relevant type II superconductors ? continues to be a research priority in understanding and applying these materials, most notably high-temperature cuprates. A particular aspect being explored by various groups is the nature of the non-superconducting cores of these flux quanta, which is still not completely understood but is already known to affect the interactions between flux quanta and thus the nature of phase transitions in ?flux matter? under various conditions. One rarely studied aspect of flux cores which this project is uniquely poised to explore is the effect of cores particularly on the field dependence of flux flow resistivity, which is the DC-driven dissipation associated with the free flux flow (FFF) phase, a highly ordered dynamic phase wherein the elasticity of the flux matter overcomes disorder-inducing pinning and thermal fluctuations. Complementing the DC transport measurements are magnetization, heat capacity, and NMR on the same samples ? via present and future collaborations. All this is to be performed on already available, high-quality, crystals of at least four different materials to explore compound-dependent subtleties. The ultimate goal is to provide a uniquely comprehensive view into the nature of the flux core. The project is also designed to provide research experience to physics undergraduates in preparation for graduate studies and beyond; therefore students are to be actively involved.