We describe a simple process for the fabrication of ultrathin, transparent, optically homogeneous, electrically conducting films of pure single-walled carbon nanotubes and the transfer of those films to various substrates. For equivalent sheet resistance, the films exhibit optical transmittance comparable to that of commercial indium tin oxide in the visible spectrum, but far superior transmittance in the technologically relevant 2- to 5-micrometer infrared spectral band. These characteristics indicate broad applicability of the films for electrical coupling in photonic devices. In an example application, the films are used to construct an electric field-activated optical modulator, which constitutes an optical analog to the nanotube-based field effect transistor.

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Measurements of magnetic noise emanating from ferromagnets due to domain motion

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We have engineered an antiferromagnetic domain wall by utilizing a magnetic frustration effect of a thin iron cap layer deposited on a chromium film. Through lithography and wet etching we selectively remove areas of the Fe cap layer to form a patterned ferromagnetic mask over the Cr film. Removing the Fe locally removes magnetic frustration in userdefined regions of the Cr film. We present x-ray microdiffraction microscopy results confirming the formation of a 90° spin-density wave propagation domain wall in Cr. This domain wall nucleates at the boundary defined by our Fe mask.Antiferromagnets play a critical and growing role in much of contemporary condensed matter physics and technology. Although traditionally used in magnetic storage devices (e.g., readheads in hard drives) for their supporting role as pinning layers, antiferromagnetic materials are now being used in emerging technologies as the principal layer governing transport properties of the device, such as spin valves utilizing antiferromagnetic tunneling anisotropic magnetoresistance [1]. With the emergence of these new technologies, the ability to understand