APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

4 Jun 2007

Volume 90, Issue 23, Articles (23xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 90, 233105 (2007); http://dx.doi.org/10.1063/1.2747052 (3 pages)

Youhui Gao, Daisuke Shindo, Yuping Bao, and Kannan Krishnan
Enlarge Image | Read More
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Unusual room temperature ductility of a Zr-based bulk metallic glass containing nanoparticles

J. B. Qiang, W. Zhang, G. Q. Xie, and A. Inoue

Appl. Phys. Lett. 90, 231907 (2007); http://dx.doi.org/10.1063/1.2746071 (3 pages) | Cited 19 times

Online Publication Date: 6 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Highly ductile Zr65Al7.5Cu27.5 bulk metallic glass (BMG) containing nanometer scaled fcc phase was obtained by copper mold casting. Room temperature compression tests revealed superior mechanical properties of the alloy: yielding stress of 1670 MPa, Young’s modulus of 90 GPa, elastic strain of 2%, and especially a remarkable plasticity of over 50%. The marginal BMG is a useful model system to examine the nanocrystal coalescence model and the shear-transformation-zone model proposed for large scale plastic deformations of metallic glasses.
Show PACS
81.05.Kf Glasses (including metallic glasses)
81.05.Bx Metals, semimetals, and alloys
61.43.Fs Glasses
81.40.Lm Deformation, plasticity, and creep
81.40.Jj Elasticity and anelasticity, stress-strain relations
81.10.Fq Growth from melts; zone melting and refining

Stabilization of facial isomer of tris(8-hydroxyquinolinate)aluminum through confinement in silica-surfactant mesostructures

Le-Le Li, Chen-Jie Fang, Quan Yuan, and Chun-Hua Yan

Appl. Phys. Lett. 90, 231908 (2007); http://dx.doi.org/10.1063/1.2746420 (3 pages) | Cited 1 time

Online Publication Date: 7 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The self-assembled nanocomposites of tris(8-hydroxyquinolinate)aluminum (Alq3) confined in the silica-surfactant mesostructures are investigated. In the photoluminescence (PL) spectra, the Alq3 molecules confined in the mesostructures exhibit a significant blueshift by 50 nm compared with that of the pristine Alq3. The PL efficiency is enhanced for the nanocomposites prepared at a higher temperature. The spectral analyses reveal that fac-Alq3 molecule, which is hard to prepare due to its relatively thermodynamically unstability, is obtained with this efficient and simple method. PL decay analysis implies experimentally the lifetimes corresponding to facial and meridional isomers.
Show PACS
78.55.Hx Other solid inorganic materials
82.70.Uv Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems, (hydrophilic and hydrophobic interactions)
81.16.Dn Self-assembly

Compressive uniaxially strained silicon on insulator by prestrained wafer bonding and layer transfer

C. Himcinschi, M. Reiche, R. Scholz, S. H. Christiansen, and U. Gösele

Appl. Phys. Lett. 90, 231909 (2007); http://dx.doi.org/10.1063/1.2747182 (3 pages) | Cited 3 times

Online Publication Date: 7 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Wafer level compressive uniaxially strained silicon on insulator is obtained by direct wafer bonding of silicon wafers in cylindrically curved state, followed by thinning one of the wafers using the smart-cut process. The mapping of the wafer bow demonstrates the uniaxial character of the strain induced by the cylindrical bending. The interfacial properties are investigated by infrared transmission imaging, scanning acoustic microscopy, and transmission electron microscopy. UV-Raman spectroscopy is employed to determine the strain in the thin transferred layer as a function of radius of curvature of the initial bending.
Show PACS
78.30.-j Infrared and Raman spectra
78.40.-q Absorption and reflection spectra: visible and ultraviolet
back to top
RSS Feeds

Space charge induced gating by a leaky gate

D. Spanheimer, L. Worschech, C. R. Müller, and A. Forchel

Appl. Phys. Lett. 90, 232101 (2007); http://dx.doi.org/10.1063/1.2746065 (3 pages)

Online Publication Date: 4 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors studied the role of gate leakage on the drain current in a monolithic, unipolar GaAs/AlGaAs heterostructure based on three contacts leaky coupled to each other. Two in-plane barriers, each defined by a row of etched holes in a two-dimensional electron gas, separate the leaky gate from the central drain and the drain from the source. A pronounced decrease of the drain current sets in when the gate starts to leak associated with the space charge injected from the leaky gate.
Show PACS
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
77.22.Jp Dielectric breakdown and space-charge effects

Temperature dependent study of InAlAs–InP/GaAsSb/InP double heterojunction bipolar transistors

Che-ming Wang, Yue-Ming Hsin, Haijun Zhu, J. M. Kuo, and Y. C. Kao

Appl. Phys. Lett. 90, 232102 (2007); http://dx.doi.org/10.1063/1.2746073 (3 pages)

Online Publication Date: 4 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
InAlAs–InP/GaAsSb/InP double heterojunction bipolar transistors (HBTs) with InAlAs–InP composite emitter have been grown, fabricated, and characterized at various temperatures from 77 to 400 K. The InAlAs–InP composite emitter structure effectively reduces electron pileup in the InP/GaAsSb base-emitter junction and hence increases current gain, especially in the low-base-current region. The turn-on voltage shows a slightly different temperature dependence (−1.66 mV/K) from conventional InGaAs based HBTs due to the composite emitter. The activation energy study for the base (0.74 eV) and collector currents (0.98 eV) indicates the high quality of the base layer and the effect of InAlAs–InP composite emitter.
Show PACS
85.30.Pq Bipolar transistors

Room temperature deposited indium zinc oxide thin film transistors

Yu-Lin Wang, F. Ren, Wantae Lim, D. P. Norton, S. J. Pearton, I. I. Kravchenko, and J. M. Zavada

Appl. Phys. Lett. 90, 232103 (2007); http://dx.doi.org/10.1063/1.2746084 (3 pages) | Cited 51 times

Online Publication Date: 4 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Depletion-mode indium zinc oxide (IZO) channel thin film transistors were fabricated on glass substrates from layers deposited at room temperature using rf magnetron sputtering. The threshold voltage was in the range from −5.5 to −6.5 V depending on gate dielectric (SiO2) thickness and the drain current on-to-off ratio was ∼ 105. The maximum field effect mobility in the channel was ∼ 4.5 cm2 V−1 s−1, lower than the Hall mobility of ∼ 17 cm2 V−1 s−1 in the same layers, suggesting a strong influence of scattering due to trapped charges at the SiO2-IZO interface. The low deposition and processing temperatures make these devices suitable for applications requiring flexible substrates.
Show PACS
85.30.Tv Field effect devices
81.15.Cd Deposition by sputtering

Dresselhaus spin-orbit coupling effect on the shot noise in resonant double-barrier structures

Rui Zhu and Yong Guo

Appl. Phys. Lett. 90, 232104 (2007); http://dx.doi.org/10.1063/1.2745199 (3 pages) | Cited 9 times

Online Publication Date: 4 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors have investigated the zero-frequency shot noise of current through resonant double-barrier structures. Taking into account the spin-orbit coupling (SOC) effect, general expressions for the shot noise in fully phase-coherent mesoscopic conductors are derived based on the scattering approach. It is found that the Dresselhaus SOC can greatly affect the average current I, shot noise S, and Fano factor of resonant diode structures. A large shot noise suppression with the Fano factor below 0.5 observed experimentally can be illustrated by the influence of the Dresselhaus SOC effect.
Show PACS
85.30.Kk Junction diodes
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
85.75.Mm Spin polarized resonant tunnel junctions
85.30.De Semiconductor-device characterization, design, and modeling

Parallel preparation of highly spin-polarized electrons in single InAs/GaAs quantum dots

W. Löffler, M. Hetterich, C. Mauser, S. Li, T. Passow, and H. Kalt

Appl. Phys. Lett. 90, 232105 (2007); http://dx.doi.org/10.1063/1.2746405 (3 pages) | Cited 9 times

Online Publication Date: 5 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Initialization of electron spins in semiconductor quantum dots (QDs) is a major prerequisite for a successful implementation of such QDs in quantum information applications. It is essential that the initialization is achieved for many individually separable dots in parallel. Here the authors show that exactly this can be accomplished with near-unity fidelity by electrical spin injection from the diluted magnetic semiconductor ZnMnSe into InAs/GaAs quantum dots. The deviation from unity is smaller than 0.13, more precise determination is limited by the signal-to-noise ratio of their setup. They demonstrate the robust concurrent initialization of several quantum dots with the same high fidelity.
Show PACS
73.63.Kv Quantum dots
72.25.Dc Spin polarized transport in semiconductors

InAsSb/GaSb heterostructure based mid-wavelength-infrared detector for high temperature operation

Y. Sharabani, Y. Paltiel, A. Sher, A. Raizman, and A. Zussman

Appl. Phys. Lett. 90, 232106 (2007); http://dx.doi.org/10.1063/1.2746951 (3 pages) | Cited 10 times

Online Publication Date: 5 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The properties of a midinfrared photodetector, based on a lattice matched n-N InAs0.91Sb0.09/GaSb type-II heterostructure, were investigated. The relatively simple two layer structure shows very promising characteristics for sensitive and dual color infrared detection. I-V characteristics and spectral response were measured at the temperature range of 10–300 K. High zero-bias resistance area product R0A of 2.5 Ω cm2 was obtained at room temperature. The measured background limited infrared photodetection temperature was 180 K corresponding to 4.1 μm cutoff. Shot and Johnson noise limited detectivities corresponding to InAsSb absorption were measured to be 1.3×1010 and 4.9×109 cm Hz1/2 W−1 at 180 and 300 K, respectively. An enhanced optical response with gain larger than unity was observed below 120 K. Bias tunable dual color detection was demonstrated at all measured temperatures.
Show PACS
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz Photodetectors (including infrared and CCD detectors)
07.60.Dq Photometers, radiometers, and colorimeters

Thermoelectric properties and electronic structure of Zintl compound BaZn2Sb2

Xiao-Jun Wang, Mei-Bo Tang, Jing-Tai Zhao, Hao-Hong Chen, and Xin-Xin Yang

Appl. Phys. Lett. 90, 232107 (2007); http://dx.doi.org/10.1063/1.2746408 (3 pages) | Cited 24 times

Online Publication Date: 6 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Polycrystalline sample of the title compound was prepared and its thermoelectric properties from 2 to 675 K were investigated. This Zintl compound shows rather low thermal conductivity, 1.6 W m−1 K−1, at room temperature. The value of its thermoelectric figure of merit ZT reaches 0.31 at 675 K. Its electronic structure, calculated by ab initio methods, suggests that the electrical transport are mainly ascribe to [Zn2Sb2] framework for p-type BaZn2Sb2. The heat capacity curve at low temperature was fitted lineally to obtain Debye temperature (about 208 K). It provides the authors with a host lattice for modification and optimization the thermoelectric properties through substitution and/or doping.
Show PACS
72.20.Pa Thermoelectric and thermomagnetic effects
71.20.Nr Semiconductor compounds
72.80.Jc Other crystalline inorganic semiconductors
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
65.40.Ba Heat capacity
71.15.-m Methods of electronic structure calculations

Solution deposited liquid crystalline semiconductors on a photoalignment layer for organic thin-film transistors

Takenori Fujiwara, Jason Locklin, and Zhenan Bao

Appl. Phys. Lett. 90, 232108 (2007); http://dx.doi.org/10.1063/1.2746937 (3 pages) | Cited 21 times

Online Publication Date: 6 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Highly ordered liquid crystalline semiconductors on a light induced alignment layer results in an anisotropic electrical characteristic and an enhanced mobility of solution processed thin-film transistors. In the case of poly-9,9′-dioctyl-fluorene-co-bithiophene, a mobility as high as 0.02 cm2 V−1 s−1 has been achieved by aligning a polymer chain parallel to the charge transport direction. Using an oligomeric semiconductor, 5,5′-bis(4-octyloxyphenyl)bithiophene, an enhanced mobility of 0.05 cm2 V−1 s−1 was obtained by the alignment of the π-π intermolecular packing direction parallel to the charge transport direction.
Show PACS
85.30.Tv Field effect devices

Intra- and intertube tunneling transport in ropes of single-walled carbon nanotubes

K. M. Seemann, J. Ebbecke, A. L. Hörner, and A. Wixforth

Appl. Phys. Lett. 90, 232109 (2007); http://dx.doi.org/10.1063/1.2746963 (3 pages)

Online Publication Date: 6 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors report on intra- and intertube tunneling induced current oscillations in an individual rope of single-walled carbon nanotubes. Defects within single tubes and tube-tube contacts provide tunneling barriers of different transparencies and heights, respectively, and the formation of quantum dots in between. As a function of the bias voltage, the authors observe a transition from an intratube to an intertube tunneling dominated transport. The samples were fabricated on prepatterned silicon substrates employing surface acoustic wave induced streaming leading to an alignment of the ropes with respect to the contacts.
Show PACS
73.40.Gk Tunneling
73.63.Fg Nanotubes
73.63.Kv Quantum dots

Enhancement of quantum efficiency of organic light emitting devices by doping magnetic nanoparticles

Cheng-Jun Sun, Yue Wu, Zhihua Xu, Bin Hu, Jianmin Bai, Jian-Ping Wang, and Jian Shen

Appl. Phys. Lett. 90, 232110 (2007); http://dx.doi.org/10.1063/1.2746415 (3 pages) | Cited 6 times

Online Publication Date: 6 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Magnetic nanoparticles of CoFe are used as dopants to enhance the quantum efficiency of electroluminance in a single layer organic light emitting device (OLED). The enhancement of quantum efficiency increases with both increasing density of CoFe nanoparticles and external magnetic field. For a given OLED with 0.1 wt % doping, the enhancement of the quantum efficiency reaches ∼ 27% and ∼ 32% without and with a magnetic field, respectively. The origin of these improvements could be attributed to the simultaneous increases of the portion of excitons among total charge carriers and the fraction of singlets among the total excitons
Show PACS
85.60.Jb Light-emitting devices

Linear electric molten zone in semiconductors

António M. Vallêra, Jorge Maia Alves, João M. Serra, Miguel C. Brito, and Roberto M. Gamboa

Appl. Phys. Lett. 90, 232111 (2007); http://dx.doi.org/10.1063/1.2747181 (3 pages) | Cited 2 times

Online Publication Date: 7 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter describes how the temperature dependence of the electrical conductivity in semiconductors may be used to produce a linear floating molten zone which is intrinsically stable and uniform along its length. An analytical model and an experimental demonstration of such electric molten zone are both presented. This effect may be of particular interest for crystal growth and semiconductor recrystallization.
Show PACS
81.05.Cy Elemental semiconductors
81.10.Fq Growth from melts; zone melting and refining
72.80.Cw Elemental semiconductors

Study of the thermal stress in a Pb-free half-bump solder joint under current stressing

B. Y. Wu, Y. C. Chan, H. W. Zhong, M. O. Alam, and J. K. L. Lai

Appl. Phys. Lett. 90, 232112 (2007); http://dx.doi.org/10.1063/1.2747183 (3 pages) | Cited 5 times

Online Publication Date: 7 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The thermal stress in a Sn3.5Ag1Cu half-bump solder joint under a 3.82×108 A/m2 current stressing was analyzed using a coupled-field simulation. Substantial thermal stress accumulated around the Al-to-solder interface, especially in the Ni+(Ni,Cu)3Sn4 layer, where a maximal stress of 138 MPa was identified. The stress gradient in the Ni layer was about 1.67×1013 Pa/m, resulting in a stress migration force of 1.82×10−16 N, which is comparable to the electromigration force, 2.82×10−16 N. Dissolution of the Ni+(Ni,Cu)3Sn4 layer, void formation with cracks at the anode side, and extrusions at the cathode side were observed.
Show PACS
81.05.Bx Metals, semimetals, and alloys
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.M- Structural failure of materials
back to top
RSS Feeds

Study of the transport properties of annealed (Ga,Mn)As by x-ray absorption spectroscopy

C. J. Ji, X. C. Cao, Q. F. Han, K. Qiu, F. Zhong, X. H. Li, H. T. He, J. N. Wang, and Y. Q. Wang

Appl. Phys. Lett. 90, 232501 (2007); http://dx.doi.org/10.1063/1.2746070 (3 pages) | Cited 3 times

Online Publication Date: 4 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A systematic Mn L-edge x-ray absorption is carried out on carefully prepared Ga0.946Mn0.054As ferromagnetic semiconductors with varying As2/Ga flux ratio. It is found that the L3 peak of the absorption spectroscopy is enhanced after low temperature (LT) annealing. Furthermore it is shown that a more localized electronic structure nearly like the d5 high-spin state is obtained. It can be attributed to breaking the MnS–MnI pairs during the annealing process. Furthermore the authors present a direct evidence for a slightly increase of the Mn substitutional concentration due to LT annealing.
Show PACS
61.72.Cc Kinetics of defect formation and annealing
75.50.Pp Magnetic semiconductors
75.50.Dd Nonmetallic ferromagnetic materials
72.20.Fr Low-field transport and mobility; piezoresistance

Computer calculation of the Lorentz microscopy image and magnetic domain structure of weakly ordered FePt:C thin film

M. C. Kim, S. J. Oh, J. K. Park, and J. M. Yang

Appl. Phys. Lett. 90, 232502 (2007); http://dx.doi.org/10.1063/1.2746078 (3 pages)

Online Publication Date: 4 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A computer calculation technique of Lorentz microscopy image was developed and was applied to the analysis of the Lorentz microscopy image and magnetic domain structure of a weakly ordered FePt:C thin film for recording media. The magnetic domain structure was, at the as-deposited (random) state, a vortex network structure and evolved into the islandlike elongated reverse domain structure at the dc-demagnetization state, via a featherlike ripple structure at the remanent state. The magnetization reversal occurred not by the domain wall motion but by the local magnetization rotation to form a series of local vortices leading to the formation of reverse domains.
Show PACS
75.50.Bb Fe and its alloys
75.70.Ak Magnetic properties of monolayers and thin films
75.60.Ch Domain walls and domain structure
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.60.Jk Magnetization reversal mechanisms

Localized laser trimming of critical current in niobium based Josephson devices

C. Granata, A. Vettoliere, L. Petti, M. Rippa, B. Ruggiero, P. Mormile, and M. Russo

Appl. Phys. Lett. 90, 232503 (2007); http://dx.doi.org/10.1063/1.2746060 (3 pages)

Online Publication Date: 6 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A thermal annealing technique for Nb/Al–AlOx/Nb Josephson devices based on laser heating is presented. This technique allows “locally” modifying the Josephson critical current density, which is not possible using standard procedures based on oven or hot plate heating. In fact, the heating of a single circuit element with a good spatial resolution is possible. At room temperature, the selected junction is exposed to a focused Ar+ laser beam aligned by an optical system. A thermographic imaging allows controlling the temperature distribution on the whole chip. Experimental results on high quality Josephson junction measured in liquid helium have shown a continuous reduction of the critical current density up to about 40%. Neighboring junctions have not exhibited any measurable change ensuring the capability to locally modify the Josephson critical current density. As first application, the present technique has been employed to recover noisy dc superconducting quantum interference device magnetometers with nonoptimal critical current values obtaining a reduction of the spectrum density of magnetic field noise from about 30 to 2.5 fT/Hz1/2.
Show PACS
85.25.Dq Superconducting quantum interference devices (SQUIDs)
85.25.Cp Josephson devices

Variation of thin film edge magnetic properties with patterning process conditions in Ni80Fe20 stripes

Brian B. Maranville, Robert D. McMichael, and David W. Abraham

Appl. Phys. Lett. 90, 232504 (2007); http://dx.doi.org/10.1063/1.2746406 (3 pages) | Cited 13 times

Online Publication Date: 6 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors report the effect of etch depth on the magnetic properties of thin film edges in magnetic nanostructures. In transversely magnetized stripes of 20-nm-thick Ni80Fe20, they use ferromagnetic resonance spectroscopy to measure the edge saturation field and effective out-of-plane stiffness field of the trapped-spin-wave edge mode as a function of ion etch depth. With increasing etching depth, the edge surface angle changes from 47° to 80°, and the field required to saturate the edge magnetization perpendicular to the stripe axis nearly doubles. This trend is largely confirmed by micromagnetic modeling of the edge geometry.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Ds Spin waves
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.50.Bb Fe and its alloys
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance

Reversible and irreversible current induced domain wall motion in CoFeB based spin valves stripes

S. Laribi, V. Cros, M. Muñoz, J. Grollier, A. Hamzić, C. Deranlot, A. Fert, E. Martínez, L. López-Díaz, L. Vila, G. Faini, S. Zoll, and R. Fournel

Appl. Phys. Lett. 90, 232505 (2007); http://dx.doi.org/10.1063/1.2746952 (3 pages) | Cited 20 times

Online Publication Date: 6 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The authors present results on current induced domain wall motion in Co/Cu/CoFeB trilayered stripes. The threshold current densities are around 106 A/cm2 at zero field, i.e., about two orders of magnitude smaller than in single NiFe stripes. The domain wall motion is assisted when the field torque acts in the same direction as the spin torque. When the field torque is opposed to the spin transfer one and above a threshold field, the authors observe a reversible displacement of the domain wall (peak in the dV/dI measurements). This can be ascribed to the onset of domain wall fluctuations, which is confirmed by micromagnetic simulations.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Ch Domain walls and domain structure
75.50.Bb Fe and its alloys

Magnetoresistive anisotropy and magnetoresistivity in strained La0.65Ca0.35MnO3 films near the metal-insulator transition

M. Egilmez, R. Patterson, K. H. Chow, and J. Jung

Appl. Phys. Lett. 90, 232506 (2007); http://dx.doi.org/10.1063/1.2746956 (3 pages) | Cited 23 times

Online Publication Date: 7 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Magnetotransport properties of strained La0.65Ca0.35MnO3 thin films with thickness between 10 and 1000 nm were investigated at temperatures near the metal-insulator transition and in magnetic fields up to 0.7 Tesla. The reduction of the thin film thickness, which in turn produces an increasing epitaxial lattice strain, dramatically increases the “in-plane” magnetic anisotropy and the magnetoresistivity.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.30.Gw Magnetic anisotropy
72.20.My Galvanomagnetic and other magnetotransport effects
68.60.Bs Mechanical and acoustical properties
71.30.+h Metal-insulator transitions and other electronic transitions

Ferromagnetic chaoite macrotubes prepared at low temperature and pressure

Shandong Li, Zhigao Huang, Liya Lü, Fengming Zhang, Youwei Du, Yuanfeng Cai, and Yuguan Pan

Appl. Phys. Lett. 90, 232507 (2007); http://dx.doi.org/10.1063/1.2746948 (3 pages) | Cited 2 times

Online Publication Date: 11 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Chaoite, a rare allotrope of carbon, is considered as a high-temperature phase abundant in circumstellar shells and is difficult to be synthesized at low temperature. However, in this study, chaoite phase was synthesized by quenching the pyrolysate of acetylene gas at low temperature and pressure. The typical morphology is a tube with 20–60 μm in diameter and more than 8 mm in length. Another interesting feature of these carbon macrotubes (CMTs) is the unexpected but clear intrinsic ferromagnetism. The ferromagnetism of sp-hybridized CMTs indicates that the sp-hybridized structure may be an origin of ferromagnetism.
Show PACS
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Cr Saturation moments and magnetic susceptibilities
75.50.Dd Nonmetallic ferromagnetic materials
81.40.Gh Other heat and thermomechanical treatments
back to top
RSS Feeds

Leakage currents at crystallites in ZrAlxOy thin films measured by conductive atomic-force microscopy

O. Bierwagen, L. Geelhaar, X. Gay, M. Piešiņš, H. Riechert, B. Jobst, and A. Rucki

Appl. Phys. Lett. 90, 232901 (2007); http://dx.doi.org/10.1063/1.2746058 (3 pages) | Cited 17 times

Online Publication Date: 4 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The spatial distribution of the leakage current through ZrAlxOy thin films with different degrees of crystallinity was investigated at the nanometer-scale. Conductive atomic-force microscopy shows leakage currents at low electric fields in the polycrystalline but not in the amorphous films. Leakage occurs at large crystallites that protrude from the surface. Ring-shaped current distributions around some of the crystallites suggest a conduction at the boundary of crystalline grain and amorphous matrix, and not through the grain. In contrast, the leakage spots that are observed in amorphous films at high electric fields are not correlated to the morphology.
Show PACS
73.61.-r Electrical properties of specific thin films
73.63.Bd Nanocrystalline materials
68.37.Ps Atomic force microscopy (AFM)
68.55.-a Thin film structure and morphology
61.46.Hk Nanocrystals
61.43.-j Disordered solids

High-density capacitors based on amorphous BaTiO3 layers grown under hydrogen containing atmosphere

P. Gonon and F. El Kamel

Appl. Phys. Lett. 90, 232902 (2007); http://dx.doi.org/10.1063/1.2746066 (3 pages) | Cited 11 times

Online Publication Date: 4 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Addition of hydrogen (H2) during the sputter deposition of BaTiO3 amorphous thin films drastically modifies their dielectric properties. Films grown under hydrogen containing atmospheres display large capacitances (several μF/cm2 for 1 μm thick films), that are hundred times higher than capacitances measured for films grown without hydrogen. This is explained by the formation of a double-layer capacitor which arises from mobile protons (protonic conduction with an activation energy around 0.3 eV). These films could find applications for the elaboration of integrated supercapacitors.
Show PACS
84.32.Tt Capacitors

Double hysteresis loop in Cu-doped K0.5Na0.5NbO3 lead-free piezoelectric ceramics

Dunmin Lin, K. W. Kwok, and H. L. W. Chan

Appl. Phys. Lett. 90, 232903 (2007); http://dx.doi.org/10.1063/1.2746087 (3 pages) | Cited 42 times

Online Publication Date: 4 June 2007

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter the authors report the observation of double hysteresis loops in Cu-doped K0.5Na0.5NbO3 (KNN) ceramics. Unlike other ferroelectric titanates (e.g., BaTiO3), aging is not required for the ceramic to exhibit the double-loop-like characteristics. Based on the symmetry-conforming principle of point defects, it is suggested that defect dipoles are formed by the acceptor dopant ions-Cu2+ and O2− vacancies along the polarization direction after the diffuse tetragonal-orthorhombic phase transition of the ceramic. Because of the low migration rates of defects, the defect dipoles remain in the original orientation during the P-E loop measurement, providing a restoring force to reverse the switched polarization. The defect dipoles also provide “pinning” effects in the normal piezoelectric activities. As a result, the ceramic becomes “hardened,” exhibiting an extraordinarily high mechanical quality factor (2500), while the other piezoelectric properties remain reasonably good: electromechanical coupling coefficients kp = 39%, kt = 47%, and piezoelectric coefficient d33 = 82 pC/N.
Show PACS
77.80.Dj Domain structure; hysteresis
77.65.Bn Piezoelectric and electrostrictive constants
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ej Polarization and depolarization
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close