SPIN ELECTRONICS: Carbon Nanotube Based Spin Electronic Devices

这份提案是对21世纪自旋电子倡议计划NSF 02-036的响应。该提案着重于两种原型碳纳米管自旋电子器件的制备和表征：纳米管自旋晶体管和纳米螺旋磁场传感器。对于分子规模的自旋电子应用，碳纳米管具有令人信服的优势。碳纳米管是准一维晶线，具有低密度的自旋散射中心。因此，电流流经纳米管时，电子或自旋散射事件很少。这使得碳纳米管可用于分子规模的自旋传输线，在长距离传输时自旋检测信号保持高水平。通过选通纳米管来改变电子密度，可以放大或抑制自旋信号。高弹道电流也会在碳纳米管电路中产生异常大的磁矩。这对于磁存储和开关应用是有用的，以放大和感测局部磁场。纳米管自旋晶体管是具有场效应栅的铁磁接触的纳米管。栅极偏置改变上下自旋通道的传输，并起到放大或抑制自旋检测信号的作用。纳米螺旋磁传感器是一种电接触的碳纳米管，生长成螺旋形。由于缺乏电子散射，电流流过螺旋产生一个巨大的轨道自旋矩，它与外加磁场发生强烈的相互作用。这极大地改变了两个磁场方向之间的阻力，即使是在低外加磁场下也是如此。总而言之，这些设备显示了一系列行为，这些行为将有助于在分子尺度上进行先进的自旋电子应用。为了完成这项工作，PI将结合他们在碳纳米管自旋传输、纳米管器件制造、纳米管电学表征和纳米管器件建模方面的集体经验。他们将与杜克大学和加州大学河滨分校化学系的合作者密切合作，优化纳米管的生长、用于电学表征的纳米管的分布，以及用于旋转电子设备应用的纳米管的化学表面改性。作为他们项目的一部分，他们将在令人兴奋的自旋电子学和纳米技术领域培训两名研究生。本科生和研究生的课程包括纳米级制造、器件建模和电气/光学表征，将结合他们的自旋电子研究进展。

This proposal was received in response to the Spin Electronics for the 21st century Initiative Program Solicitation NSF 02-036. The proposal focuses on fabrication and characterization of two prototype carbon nanotube spin electronic devices: the nanotube spin transistor and the nano-helix magnetic field sensor. For molecular scale spin electronic applications, the carbon nanotube has compelling advantages. Carbon nanotubes are quasi-one-dimensional, crystalline wires having a low density of spin scattering centers. Therefore, current flows through nanotubes with very few electron or spin scattering events. This makes carbon nanotubes useful for molecular scale spin transmission lines, with spin detection signals remaining high over long transmission distances. Spin signals can be amplified or suppressed by gating the nanotube to change the electron density. High ballistic current flow also produces anomalously large magnetic moments in carbon nanotube circuits. This is useful for magnetic memory and switching applications to amplify and sense local magnetic fields.The nanotube spin transistor is a ferromagnetically contacted nanotube with a field effect gate. The gate bias modifies the transmission of the up and down spin channels, and acts to amplify or suppress the spin detection signal. The nano-helix magnetic sensor is an electrically contacted carbon nanotube grown into a helical shape. Due to the lack of electron scattering, current flow through the helix produces a giant orbital spin moment, which interacts strongly with applied magnetic field. This dramatically alters the resistance between the two field directions, even for low applied fields. Together, these devices display a range of behavior that will be useful for advanced spin electronic applications on the molecular scale. To accomplish this work, the PIs will combine their collective experience in carbon nanotube spin transport, nanotube device fabrication, nanotube electrical characterization and nanotube device modeling. They will work closely with collaborators within the chemistry departments at Duke University and UC Riverside to optimize nanotube growth, distribution of nanotubes for electrical characterization, and chemical surface modification of nanotubes for spin electronic device applications. As part of their project, they will be training two graduate students in the exciting area of spin electronics and nanoscale technology. The undergraduate and graduate curriculum including Nanoscale fabrication, Device Modeling, and Electrical/ Optical Characterization will incorporate their spin electronic research advances.