Emergent 1/f Noise in Ensembles of Random Telegraph Noise Oscillators.

The emergence of 1/f noise from an aggregate of 1/f^{2} noise signals in magnetic nanodots undergoing random telegraph oscillations in their magnetization is reported. This emergence is found to occur with as few as two random telegraph noise (RTN) oscillators producing 1/f noise across two decades of frequency bandwidth, and with fewer than ten such oscillators producing 1/f noise across over four decades. The RTN fluctuations observed are as small as one part in 10 000 compared to dc voltage signals but still generate easily observable 1/f noise at up to 10^{5} Hz. These observations may explain the historic difficulty in identifying RTN oscillator sources of 1/f noise.

Gas-assisted electron-beam-induced nanopatterning of high-quality titanium oxide.

Electron-beam-induced deposition of titanium oxide nanopatterns is described. The precursor is titanium tetra-isopropoxide, delivered to the deposition point through a needle and mixed with oxygen at the same point via a flow through a separate needle. The depositions are free of residual carbon and have an EDX determined stoichiometry of TiO2.2. High resolution transmission electron microscopy and Raman spectroscopy studies reveal an amorphous structure of the fabricated titanium oxide. Ellipsometric characterization of the deposited material reveals a refractive index of 2.2-2.4 RIU in the spectral range of 500-1700 nm and a very low extinction coefficient (lower than 10(-6) in the range of 400-1700 nm), which is consistent with high quality titanium oxide. The electrical resistivity of the titanium oxide patterned with this new process is in the range of 10-40 GΩ cm and the measured breakdown field is in the range of 10-70 V µm(-1). The fabricated nanopatterns are important for a variety of applications, including field-effect transistors, memory devices, MEMS, waveguide structures, bio- and chemical sensors.

Gas-assisted electron-beam-induced nanopatterning of high-quality Si-based insulator.

An oxygen-assisted electron-beam-induced deposition (EBID) process, in which an oxygen flow and the vapor phase of the precursor, tetraethyl orthosilicate (TEOS), are both mixed and delivered through a single needle, is described. The optical properties of the SiO(2+δ) (- 0.04 ≤ δ ≤ +0.28) are comparable to fused silica. The electrical resistivity of both single-needle and double-needle SiO(2+δ) are comparable (greater than 7 GΩ cm) and a measured breakdown field is greater than 400 V µm(-1). Compared to the double-needle process the advantage of the single-needle technique is the ease of alignment and the proximity to the deposition location, which facilitates fabrication of complex 3D structures for nanophotonics, photovoltaics, micro- and nano-electronics applications.

A simple technique to measure the magnetic susceptibility of liquids.

A novel technique for measuring the magnetic susceptibility of liquids with modest applied magnetic fields (order of 0.25 T) is presented. The deformation of the liquid surface by a magnetic field is determined by a laser bounce or optical lever technique. The energy balance between the magnetic energy and the gravitational potential of the diamagnetic or paramagnetic liquid interaction is used to determine the susceptibility. The energy due to the surface tension energy is about 10% of the gravitational energy and can be neglected for fast measurements.