Vortex Pinning in Thin Film Superconductors by Controlled Pinning Structures

本实验研究项目是利用可控钉钉结构研究薄膜超导体中的涡流钉钉问题。本文是对人工钉钉作用下的低、高Tc薄膜涡旋物理特性的实验与理论联合研究。钉接结构采用最先进的光刻工艺设计。所研究的钉钉结构包括规则的和弱无序的“孔”阵列，和/或由正常或磁性材料制成的“条纹”。这些阵列在广泛的温度、场和材料参数范围内的钉住特性将通过传输、噪声和直接成像测量来表征。采用新颖的钉钉模式，将钉钉相扩展到较宽的磁场范围，超出了标称的匹配场，以增强涡流钉钉。它们还提供了新的“媒介”，可以研究各种新的、有趣的涡旋现象。理论是这个项目的固有部分。新的制造方法和设备将使用最先进的薄膜技术和最先进的光刻工艺来开发。这个研究项目本质上是跨学科的，涉及到一些预科和研究生的研究人员。他们将熟悉适用于凝聚态物理、微电子、磁记录和传感器以及超导器件的研究设备和方法。他们的培训将为他们在工业、政府实验室或学术界的职业生涯做好充分的准备。本实验基础研究项目是关于提高超导薄膜的载流能力。超导体在磁场存在下的“临界”电流受到“钉住中心”的影响，“钉住中心”充当穿透薄膜的磁通量线（涡流）的锚点。临界电流可以通过增加钉接来提高。本文研究了薄膜超导体中可控钉钉结构的涡旋钉钉。本文是对人工钉钉作用下的低、高Tc薄膜涡旋物理特性的实验与理论联合研究。钉接结构采用最先进的光刻工艺设计。所研究的钉钉结构包括规则的和弱无序的“孔”阵列，和/或由正常或磁性材料制成的“条纹”。这些阵列在广泛的温度、场和材料参数范围内的钉住特性将通过传输、噪声和直接成像测量来表征。采用新颖的钉钉模式，将钉钉相扩展到较宽的磁场范围，超出了标称的匹配场，以增强涡流钉钉。它们还提供了新的“媒介”，可以研究各种新的、有趣的涡旋现象。理论是这个项目的固有部分。新的制造方法和设备将使用最先进的薄膜技术和最先进的光刻工艺来开发。这个研究项目本质上是跨学科的，涉及到一些预科和研究生的研究人员。他们将熟悉适用于凝聚态物理、微电子、磁记录和传感器以及超导器件的研究设备和方法。他们的培训将为他们在工业、政府实验室或学术界的职业生涯做好充分的准备。＊＊＊

w:\awards\awards96\*.doc 9801921 Schuller This experimental research project is concerned with vortex pinning in thin film superconductors by controlled pinning structures. It is a joint experimental/theoretical study of the physics of vortices in low and high Tc thin films subject to artificial pinning. The pinning structure is engineered using state-or-the-art lithography processes. Pinning structures under study include regular and weakly disordered arrays of "holes", and/or "stripes" made of normal or magnetic materials. The pinning characteristics of these arrays over a wide range of temperature, field and materials parameters will be characterized by transport, noise, and direct imaging measurements. Novel pinning patterns will be used to expand the pinned phase to a broad range of magnetic fields, beyond the nominal matching field, to enhance vortex pinning. They also provide new "media" in which a variety of new and interesting vortex phenomena can be studied. Theory is an inherent part of the project. New fabrication methods and devices will be developed using state of the art thin film techniques together with forefront lithography processes. This research program is interdisciplinary in nature and involves several pre- and post-graduate researchers in its activities. They will become familiar with research equipment and methods applicable to condensed matter physics, microelectronics, magnetic recording and sensors, and superconducitng devices. Their training will be excellent preparation for careers in industry, government laboratories or academia. %%% This experimental basic research project is concerned with increasing the current carrying capacity of superconducting thin films. The "critical" current of a superconductor in the presence of a magnetic field is influenced by "pinning centers" which act as anchors fo r the magnetic flux lines (vortices) which penetrate the thin film. The critical current can be increased by increasing the pinning. This study investigates vortex pinning in thin film superconductors by controlled pinning structures. It is a joint experimental/theoretical study of the physics of vortices in low and high Tc thin films subject to artificial pinning. The pinning structure is engineered using state-or-the-art lithography processes. Pinning structures under study include regular and weakly disordered arrays of "holes", and/or "stripes" made of normal or magnetic materials. The pinning characteristics of these arrays over a wide range of temperature, field and materials parameters will be characterized by transport, noise, and direct imaging measurements. Novel pinning patterns will be used to expand the pinned phase to a broad range of magnetic fields, beyond the nominal matching field, to enhance vortex pinning. They also provide new "media" in which a variety of new and interesting vortex phenomena can be studied. Theory is an inherent part of the project. New fabrication methods and devices will be developed using state of the art thin film techniques together with forefront lithography processes. This research program is interdisciplinary in nature and involves several pre- and post-graduate researchers in its activities. They will become familiar with research equipment and methods applicable to condensed matter physics, microelectronics, magnetic recording and sensors, and superconducitng devices. Their training will be excellent preparation for careers in industry, government laboratories or academia. ***