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We prepared giant magnetoresistance samples comprising of pseudo spin valve structures and measured the current-perpendicular-to-plane magnetoresistance (MR) with applied magnetic field along the easy and hard axes of the samples. When the magnetic field was applied along the easy axis, high and low resistance states representing magnetization parallel and anti-parallel states were observed. However, when the magnetic field was applied along the hard axis, two stochastic MR curves were obtained. The two distinct MR curves correspond to the different magnetizations reversal processes via two kinds of the magnetization orientation states, fully parallel and anti-parallel, at remanence. In our case, the two distinct magnetization reversal processes occurred randomly. [ABSTRACT FROM AUTHOR]

A novel vacuum field-emission differential amplifier (duff-amp) based on carbon-nanotube (CNT) emitters has been developed, modeled, and its ac performance characterized. A dual-mask microfabrication process was employed to achieve a single-chip diff-amp by integrating matched CNT field-emission triodes with built-in split gates and integrated anodes. The identical pair of triode amplifiers was well matched in device characteristics. The measured ac common-mode-rejection ratio (CMRR) of the diff-amp was ∼50 dB. The proposed CMRR semianalytical model was validated with the experimental data. The successful implementation of the CNT diff-amp demonstrates a new way to achieve high-temperature and radiation-tolerant vacuum integrated circuits. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate high-performance giant magnetoresistive spin transistor (GMRST) and magnetotunneling resistive spin transistor (MTRST) which could be used as magnetic pickup head and magnetoresistive random access memory (MRAM). This kind of spin device is based on the technologies of giant magnetoresistance (GMR) and tunneling magnetoresistance (TMR) effects together with a p-n junction. The junction is used as a potential barrier to select spin electrons. In case of GMRST the collector current, Ic, varies from 464 pA at magnetically parallel state to 309 pA at magnetically antiparallel state and gives a percentage change of about 50% at room temperature. As for the MTRST, the change of Ic is about 45% at room temperature with current varying from 2.9 to 4.2 μA. Memory effect, which is the intrinsic behavior of magnetic materials, is also demonstrated. [ABSTRACT FROM AUTHOR]

We utilize the inverse proximity effect in superconductor-ferromagnet bilayer to generate lateral Josephson junctions. The weak link is created by a ferromagnetic NiFe strip across a superconductor Nb bridge due to the inverse proximity effect. The critical currents of the junctions were measured at different temperatures and magnetic fields. The junctions exhibit a modulation of the critical current in perpendicular magnetic field similar to a Fraunhofer interference pattern which proves the dc Josephson effect. The weak link region induced by the NiFe in Nb persists down to 2 K. [ABSTRACT FROM PUBLISHER]

The effects of low-temperature (210 °C-290 °C) annealing on the microstructure, lattice constant, and magnetic properties of (In0.52Al0.48)0.91Mn0.09As grown by low-temperature molecular-beam epitaxy were studied. The results show that low-temperature annealing has little influence on the crystalline structure and interface quality of (In0.52Al0.48)0.91Mn0.09As epilayer. In contrast, both the lattice constant and Curie temperature of (In0.52Al0.48)0.91Mn0.09As are found to be strongly dependent on the annealing temperature. The lattice constant linearly decreases with increasing annealing temperature; while the Curie temperature increases with increasing annealing temperature up to 250 °C, and then abruptly decreases upon further annealed at 270 °C and 290 °C. [ABSTRACT FROM AUTHOR]

Goal: To enhance endovascular navigation using surgical guidewires and the use of ionizing radiation, we demonstrate a method for ultrasonic localization of wires with diameters less than the wavelength of ultrasound in the medium. Methods: Nitinol wires with diameters ranging from 50 μm to 250 μm were imaged ultrasonically in a 0.25-in-diameter water-filled tube in a gelatin medium. Imaging frequencies were 5 MHz, 7.5 MHZ, and 10 MHz. Results: For the full range of diameters traversing the phantom, the wires were localized successfully via visual inspection of both regular and difference ultrasound images. Similarly, two convolutional neural networks were trained, and both achieved an accuracy of over 95%. Conclusions: Wires with diameters as small as 50 μm were localized successfully in a water-based gelatin phantom, indicating the potential use of ultrasound to enhance endovascular navigation and surgical treatment.