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A resistive switching ZnO n–n homojunction diode fabricated with a stack of two dissimilar ZnO thin films shows promising characteristics necessary to address the crosstalk problem in a crossbar memory array. The device has a characteristic I–V-hysteresis loop in forward bias, in conjunction with its n–n junction characteristics. In the ac frequency range of 10 Hz–15 kHz, the area inside the hysteresis loop initially increased, reaching a maximum at 1 kHz, and then decreased with increasing frequency. The maximum in the area of the hysteresis loop corresponds to the accumulation of space charge at the interface. The resistivity of the device was found to vary from 5 to 100 kΩ in the bias range of 0–10 V and in the range of 106 Ω when reverse biased; the ratio of high resistive state to low resistive state has its maximum (∼2.4) at 1 kHz ac signal at 3 V. [ABSTRACT FROM AUTHOR]

In this paper we report the superconducting quantum interference device (SQUID) and magnetic force microscope (MFM) measurements of magnetic multilayer nanoscale antidot samples. The systems used consist of Fe(60 Å)/Ni(90 Å)/Fe(60 Å) (FeNiFe) multilayer antidots with hexagonal lattice fabricated on nanochannel glass (NCG) substrates with antidot diameters of 260, 362, 530, and 800 nm. The results indicate that the domain structure is commensurate with the holes due to the pinning effect of the antidots. This pinning effect is inversely proportional to the diameter of the antidots. The field dependent MFM data show that the hexagonal antidot lattice induces a weak anisotropy with the magnetic easy axis along the nearest neighbor direction. The unit cell in the antidot arrays could be used for data storage. [ABSTRACT FROM AUTHOR]

Chemiresistors were constructed using 3-D silica nanospring mats coated with a contiguous film of ZnO nanocrystals. Chemiresistors with an average ZnO nanocrystal radius <3 nm, or >20 nm, were found to exhibit a relative change in conductance of a factor of 50 upon exposure to a gas flow of 20% O2 and 80% N2 with ∼500 ppm of toluene and an operational temperature of 400 °C. Samples with an average ZnO nanocrystal radius of 15 nm were found to be the most responsive with a relative conductance change of a factor of 1000. The addition of metal nanoparticles (average radius equal to 2.4 nm) onto the surface of the ZnO nanocrystals (average radius equal to 15 nm) produced a relative change in conductance of a factor of 1500. For the optimum conditions (T = 400 °C, grain size ∼15 nm) well-defined spikes in conductance to explosive vapors (TNT, TATP) were obtained for 0.1 ms exposure time at ppb levels. [ABSTRACT FROM AUTHOR]

Electrical properties of a chemical sensor constructed from mats of GaN nanowires decorated with gold nanoparticles as a function of exposure to Ar, N2, and methane are presented. The Au nanoparticle decorated nanowires exhibited chemically selective electrical responses. The sensor exhibits a nominal response to Ar and slightly greater response for N2. Upon exposure to methane the conductivity is suppressed by 50% relative to vacuum. The effect is fully reversible and is independent of exposure history. We offer a model by which the change in the current is caused by a change in the depletion depth of the nanowires, the change in the depletion depth being due to an adsorbate induced change in the potential on the gold nanoparticles on the surface of the nanowires. [ABSTRACT FROM AUTHOR]

Iron nanoparticles were synthesized in situ within the channels of a microchannel glass by differentially pumping across the plate in conjunction with plasma enhanced chemical vapor deposition. The microchannel glass was mounted on a custom designed differentially pumped sample holder, which produced 10 Torr of differential pressure across the 5 μm channels. The iron precursor was ferrocene [(C[sub 5]H[sub 5])[sub 2]–Fe]. The composition and structure of the nanoparticles was determined by electron diffraction to be Fe[sub 3]O[sub 4], where oxidation of the nanoparticles occurred upon exposure to air. Transmission electron microscopy revealed the formation of nanoparticles ranging in size from 150 to 960 nm, which are formed from smaller nanoparticles on the order of 5–10 nm. The large nanoparticles (150–960 nm) grow independently of one another and are largely freestanding within the channels, i.e., they are not highly attached to the channel walls or agglomerated. The magnetic signature of the large nanoparticles is consistent with ferrimagnetic Fe[sub 3]O[sub 4]. The magnetic hysteresis loops of the particles are reminiscent of superparamagnetic behavior, which would suggest that the magnetic coupling between the 5 and 10 nm nanoparticles is weak. A model for nanoparticle formation based on plasma suspension of the Fe nanoparticles inside the glass channels is proposed. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents information on a study which synthesized iron nanoparticles in an amorphous boron carbide matrix using plasma enhanced chemical vapor deposition. Nanoparticle synthesis; Experimental details; Results and discussion; Conclusions.

Presents a study which investigated spin polarization of the conduction bands and secondary electrons of gadolimium (Gd). Explanation for the polarization dip of the secondary electron spectra of Gd surfaces; Temperature dependence of the bulk bands; Correlation between spin polarization and oxygen.