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7 Jan 2008

Volume 92, Issue 1, Articles (01xxxx)

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Appl. Phys. Lett. 92, 011101 (2008); http://dx.doi.org/10.1063/1.2828458 (3 pages)

F. Pedaci, S. Barland, E. Caboche, P. Genevet, M. Giudici, J. R. Tredicce, T. Ackemann, A. J. Scroggie, W. J. Firth, G.-L. Oppo, G. Tissoni, and R. Jäger
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Nanoscale heat transfer in a thin aluminum film and femtosecond time-resolved electron diffraction

Jau Tang

Appl. Phys. Lett. 92, 011901 (2008); http://dx.doi.org/10.1063/1.2828204 (3 pages) | Cited 8 times

Online Publication Date: 2 January 2008

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We examined nanoscale heat transfer and structural dynamics by analyzing ultrafast electron diffraction data of a laser-heated aluminum film. The excellent agreement between model calculations with experimental data allows us to elucidate the mechanism of dynamic expansion/contraction involving acoustic wave propagation from the stressed bulk atoms and the more well-understood mechanism of linear thermal expansion.
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65.80.-g Thermal properties of small particles, nanocrystals, nanotubes, and other related systems
65.40.De Thermal expansion; thermomechanical effects
68.60.Dv Thermal stability; thermal effects
61.05.J- Electron diffraction and scattering
62.30.+d Mechanical and elastic waves; vibrations

Atomic structure of binary Cu64.5Zr35.5 bulk metallic glass

X. D. Wang, S. Yin, Q. P. Cao, J. Z. Jiang, H. Franz, and Z. H. Jin

Appl. Phys. Lett. 92, 011902 (2008); http://dx.doi.org/10.1063/1.2828694 (3 pages) | Cited 47 times

Online Publication Date: 2 January 2008

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Atomic structures of bulk glass-forming Cu64.5Zr35.5 and the eutectic composition Cu61.8Zr38.2 metallic glasses (MGs) have been studied by a combination of state-of-the-art experimental techniques and computational methods. Three-dimensional atomic configuration of the Cu64.5Zr35.5 MG is established. It is found that icosahedronlike clusters are dominant in both MGs. However, icosahedronlike clusters centered by Cu atoms are slightly denser packing and less distorted in Cu64.5Zr35.5, which can enhance the glass forming ability (GFA) by suppressing atomic movements and increasing the structural incompatibility with competing crystalline phases. The atomic arrangements from short to medium-range order are envisaged and compared between both MGs.
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61.43.Fs Glasses
61.43.Bn Structural modeling: serial-addition models, computer simulation

Deformation-induced grain rotation and growth in nanocrystalline Ni

Y. B. Wang, B. Q. Li, M. L. Sui, and S. X. Mao

Appl. Phys. Lett. 92, 011903 (2008); http://dx.doi.org/10.1063/1.2828699 (3 pages) | Cited 33 times

Online Publication Date: 3 January 2008

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Nanobeam electron diffraction and a series of dark field images techniques were used to investigate the deformation mechanisms of nanocrystalline (nc) Ni in response to in situ tensile deformation under transmission electron microscopy (TEM). The experiments exhibit the complete processes of individual grain rotation and neighboring grain rotation/growth. Deformation-induced grain rotation and growth as one of plastic deformation mechanisms in nc materials was revealed. At the same time, these results were confirmed further by ex situ TEM observation on deformed sample and were also better understood by physical deformation model.
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81.40.Lm Deformation, plasticity, and creep
61.46.Hk Nanocrystals
62.20.F- Deformation and plasticity

A multiaxial stretchable interconnect using liquid-alloy-filled elastomeric microchannels

Hyun-Joong Kim, Chulwoo Son, and Babak Ziaie

Appl. Phys. Lett. 92, 011904 (2008); http://dx.doi.org/10.1063/1.2829595 (3 pages) | Cited 30 times

Online Publication Date: 3 January 2008

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We report on the fabrication and characterizations of a multiaxial stretchable interconnect using room-temperature liquid-alloy-filled elastomeric microchannels. Polydimethylsiloxane (PDMS) microchannels coated at the bottom with a gold wetting layer were used as the reservoirs which were subsequently filled by room-temperature liquid alloy using microfluidic injection technique. Using a diamond-shaped geometry to provide biaxial performance, a maximum stretchability of 100% was achieved (ΔR = 0.24 Ω). Less than 0.02 Ω resistance variation was measured for 180° bending. Active electronics, light emitting diode, was also integrated onto the PDMS substrate with stretchable interconnects to demonstrate stable electrical connection during stretching, bending, and twisting.
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85.40.Ls Metallization, contacts, interconnects; device isolation
85.60.Jb Light-emitting devices
68.47.Mn Polymer surfaces
68.55.-a Thin film structure and morphology
61.25.Mv Liquid metals and alloys

Magnetic and structural properties of MnAs thin films on GaAs(111)B: Influence of the growth temperature

V. Garcia, M. Bibes, B. Vodungbo, M. Eddrief, D. Demaille, and M. Marangolo

Appl. Phys. Lett. 92, 011905 (2008); http://dx.doi.org/10.1063/1.2830012 (3 pages)

Online Publication Date: 3 January 2008

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The magnetic and structural properties of MnAs thin films grown on GaAs(111)B at different temperatures (160–280 °C) are investigated. A narrow optimum growth temperature window (200–240 °C) is found where the Curie temperature and the room temperature magnetization are maximized. High-resolution x-ray diffraction experiments are performed on the samples showing that the films are epitaxial for a minimum growth temperature of 200 °C. The room temperature fraction of the hexagonal phase is strongly dependent on the growth temperature in agreement with the magnetic properties.
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75.50.Dd Nonmetallic ferromagnetic materials
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

Formation and electrical bistability properties of ZnO nanoparticles embedded in polyimide nanocomposites sandwiched between two C60 layers

Fushan Li, Tae Whan Kim, Wenguo Dong, and Young-Ho Kim

Appl. Phys. Lett. 92, 011906 (2008); http://dx.doi.org/10.1063/1.2830617 (3 pages) | Cited 14 times

Online Publication Date: 4 January 2008

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The electrical bistability of the memory device based on ZnO nanoparticles embedded in a polyimide (PI) layer was investigated. Transmission electron microscopy and selected area electron diffraction pattern measurements showed that ZnO nanocrystals were formed inside the PI layer. Current-voltage measurements on Al/C60/ZnO nanoparticles embedded in PI layer/C60/indium tin oxide structures at 300 K showed a current bistability with a large on/off ratio of 104. The current-voltage hysteresis characteristics at negative voltages could be modified by varying the applied positive erasing voltage. The memory device fabricated utilizing ZnO nanoparticles embedded in a PI layer exhibited excellent environmental stability at ambient conditions.
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85.30.De Semiconductor-device characterization, design, and modeling

Photoinduced metallic state in VO2 proved by the terahertz pump-probe spectroscopy

M. Nakajima, N. Takubo, Z. Hiroi, Y. Ueda, and T. Suemoto

Appl. Phys. Lett. 92, 011907 (2008); http://dx.doi.org/10.1063/1.2830664 (3 pages) | Cited 17 times

Online Publication Date: 4 January 2008

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We investigated the ultrafast terahertz response to the photoexcitation for vanadium dioxide single crystals and thin films using the optical-pump terahertz-probe technique at room temperature. The optical excitation induced an ultrafast decrease of the transmittance of the terahertz radiation within 0.7 ps. Since we expect only the free carrier response in the terahertz range, the decrease of the transmittance is unambiguously assigned to the appearance of the high electronic conductivity due to free carriers. The conductivity increases more than ten times in the picosecond time range after photoexcitation and it is concluded that the electronic states are metallic.
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71.30.+h Metal-insulator transitions and other electronic transitions
78.47.J- Ultrafast spectroscopy (<1 psec)
78.70.Gq Microwave and radio-frequency interactions
78.66.Nk Insulators
73.61.Ng Insulators

Optical waveguide cantilever actuated by light

Kirill Zinoviev, Carlos Dominguez, Jose Antonio Plaza, and Laura M. Lechuga

Appl. Phys. Lett. 92, 011908 (2008); http://dx.doi.org/10.1063/1.2830818 (3 pages) | Cited 2 times

Online Publication Date: 4 January 2008

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We present experimental studies and theoretical analysis of a microcantilever working as an optical waveguide metallized from one side and actuated by light propagating inside it. Light absorbed in the metallic layer increases the temperature of the bimetallic structure and induces the cantilever bending. Dynamical properties of the cantilevers were studied using actuation by light modulated at frequencies of up to 800 Hz. The deflection of the cantilever by 400 nm was obtained while 0.25 mW of light power was coupled inside it.
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42.79.Gn Optical waveguides and couplers
07.10.Cm Micromechanical devices and systems

High pressure phase transitions and compressibilities of Er2Zr2O7 and Ho2Zr2O7

F. X. Zhang, M. Lang, U. Becker, R. C. Ewing, and J. Lian

Appl. Phys. Lett. 92, 011909 (2008); http://dx.doi.org/10.1063/1.2830832 (3 pages) | Cited 7 times

Online Publication Date: 4 January 2008

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Phase stability and compressibility of rare earth zirconates with the defect-fluorite structure were investigated by in situ synchrotron x-ray diffraction. A sluggish defect-fluorite to a cotunnitelike phase transformation occurred at pressures of ∼ 22 and ∼ 30 GPa for Er2Zr2O7 and Ho2Zr2O7, respectively. Enhanced compressibility was found for the high pressure phase as a result of increasing cation coordination number and cation-anion bond length.
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62.50.-p High-pressure effects in solids and liquids
64.70.K- Solid-solid transitions
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity

Structural anisotropy in a Zr57Ti5Cu20Al10Ni8 bulk metallic glass deformed by high pressure torsion at room temperature

Ádám Révész, Erhard Schafler, and Zsolt Kovács

Appl. Phys. Lett. 92, 011910 (2008); http://dx.doi.org/10.1063/1.2830992 (3 pages) | Cited 15 times

Online Publication Date: 4 January 2008

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Fully amorphous Zr57Ti5Cu20Al10Ni8 bulk metallic glass specimens were subjected to deformation by high pressure torsion at room temperature. Consecutive high resolution synchrotron x-ray diffraction mapping has revealed the variation of the average atomic bond length and shown no evidence of crystallization in this excellent glass former. Difference in the sign of the atomic distortion obtained in direction parallel to the sample surface and along the cross section indicates strong structural anisotropy.
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61.43.Fs Glasses
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
62.50.-p High-pressure effects in solids and liquids

Growth of stoichiometric subnanometer silica films

D. J. Stacchiola, M. Baron, S. Kaya, J. Weissenrieder, S. Shaikhutdinov, and H.-J. Freund

Appl. Phys. Lett. 92, 011911 (2008); http://dx.doi.org/10.1063/1.2824842 (3 pages) | Cited 9 times

Online Publication Date: 4 January 2008

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We present a method to grow stoichiometric SiO2 films of only ∼ 0.6–0.9 nm in thickness on a metal substrate. Based on photoelectron and infrared spectroscopy studies, we conclude that the ∼ 0.6-nm-thick silica films exhibit characteristics only observed for >2.0-nm-thick films grown on conventional Si substrates. The films can be used as model oxides for fundamental studies and may have implications on the further miniaturization of metal-oxide-semiconductor transistors.
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81.16.-c Methods of micro- and nanofabrication and processing
81.07.Bc Nanocrystalline materials
79.60.Bm Clean metal, semiconductor, and insulator surfaces
78.30.Hv Other nonmetallic inorganics
61.66.Bi Elemental solids
61.66.Dk Alloys

Growth of layered LiNi0.5Mn0.5O2 thin films by pulsed laser deposition for application in microbatteries

Hui Xia, Li Lu, and Ying Shirley Meng

Appl. Phys. Lett. 92, 011912 (2008); http://dx.doi.org/10.1063/1.2829605 (3 pages) | Cited 7 times

Online Publication Date: 4 January 2008

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LiNi0.5Mn0.5O2 films were prepared by pulsed laser deposition on stainless steel (SS) and Au substrates. The substrate was found to play an important role in determining the growth of films. Although similar x-ray diffraction spectra were observed for both types of substrates, Raman spectra exhibited different features. The charge-discharge behavior of the film on the SS substrate indicates a spinel structure while the charge-discharge behavior of the film on the Au substrate indicates a layered structure. The secondary ion mass spectrometry depth-profiling results indicate interdiffusion between the film and the substrate, which inhibits the formation of pure layered LiNi0.5Mn0.5O2 phase.
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68.55.at Other materials
81.15.Fg Pulsed laser ablation deposition
82.47.Aa Lithium-ion batteries
78.30.Am Elemental semiconductors and insulators
66.30.Ny Chemical interdiffusion; diffusion barriers
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Softening of nickel in the vicinity of its Curie point

E. Zaretsky

Appl. Phys. Lett. 92, 011913 (2008); http://dx.doi.org/10.1063/1.2829790 (3 pages) | Cited 5 times

Online Publication Date: 4 January 2008

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The dynamic yield strength of commercially pure nickel (99.5% Ni), as determined by planar impact experiments, shows a fivefold decrease in the close (±50 °C) vicinity of its Curie point. The effect is attributed to the enhanced adsorption of impurity atoms by stacking fault ribbons (Suzuki atmosphere) that takes place in a narrow temperature interval.
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81.40.Lm Deformation, plasticity, and creep
62.20.fg Shape-memory effect; yield stress; superelasticity
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.50.Cc Other ferromagnetic metals and alloys
68.43.Mn Adsorption kinetics

Few-layer graphene on SiC, pyrolitic graphite, and graphene: A Raman scattering study

C. Faugeras, A. Nerrière, M. Potemski, A. Mahmood, E. Dujardin, C. Berger, and W. A. de Heer

Appl. Phys. Lett. 92, 011914 (2008); http://dx.doi.org/10.1063/1.2828975 (3 pages) | Cited 86 times

Online Publication Date: 7 January 2008

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The results of micro-Raman scattering measurements performed on three different “graphitic” materials: microstructured disks of highly oriented pyrolytic graphite, graphene multilayers thermally decomposed from carbon-terminated surface of 4H-SiC and an exfoliated graphene monolayer are presented. Despite its multilayer character, most parts of the surface of the graphitized SiC substrates shows a single component, Lorentzian shape, double resonance Raman feature in striking similarity to the case of a single graphene monolayer. Our observation suggests a very weak electronic coupling between graphitic layers on the SiC surface, which therefore can be considered to be graphene multilayers with a simple (Dirac-like) band structure.
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78.30.Na Fullerenes and related materials
81.05.U- Carbon/carbon-based materials

Oxygen effects on plastic deformation of a Zr-based bulk metallic glass

Z. P. Lu, H. Bei, Y. Wu, G. L. Chen, E. P. George, and C. T. Liu

Appl. Phys. Lett. 92, 011915 (2008); http://dx.doi.org/10.1063/1.2828981 (3 pages) | Cited 15 times

Online Publication Date: 7 January 2008

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Starting with Zr of two different purities, Zr-based bulk metallic glasses (BMGs) with a nominal composition of Zr62Cu15.5Ni12.5Al10 were prepared having oxygen concentrations of about 3900 and 920 at. ppm, respectively. Uniaxial compression tests showed that the BMG containing the higher level of oxygen has a higher yield strength and is capable of undergoing much less plastic deformation than that containing the lower level of oxygen. It appears that oxygen suppresses the formation of multiple shear bands but leads to an inability to sustain shear-band propagation, thus, changing the failure mode from relatively ductile to catastrophic brittle fracture.
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81.40.Lm Deformation, plasticity, and creep
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.F- Deformation and plasticity
62.20.me Fatigue
62.20.mj Brittleness

Analytical model to evaluate interface characteristics of carbon nanotube reinforced aluminum oxide nanocomposites

Yao Chen, Kantesh Balani, and Arvind Agarwal

Appl. Phys. Lett. 92, 011916 (2008); http://dx.doi.org/10.1063/1.2821108 (3 pages) | Cited 8 times

Online Publication Date: 7 January 2008

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This research presents an analytical method to investigate the effect of volume fraction and the number of outer walls of multiwalled carbon nanotube (MWNT) reinforcement on load carrying capability in the aluminum oxide matrix. Interfacial shear stress transfer and energy dissipation have been estimated using the Cox model. Critical energy release rate for the debonding of MWNT from the matrix is also estimated based on the crack deflection. The computed results sufficiently manifest that MWNT pullout and crack deflection contributes greatly to improved fracture toughness of carbon nanotube reinforced aluminum oxide nanocomposites.
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81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
61.46.Fg Nanotubes

Spectroscopic ellipsometry characterization of the optical properties and thermal stability of ZrO2 films made by ion-beam assisted deposition

C. V. Ramana, S. Utsunomiya, R. C. Ewing, U. Becker, V. V. Atuchin, V. Sh. Aliev, and V. N. Kruchinin

Appl. Phys. Lett. 92, 011917 (2008); http://dx.doi.org/10.1063/1.2811955 (3 pages) | Cited 8 times

Online Publication Date: 7 January 2008

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The optical properties, interface structure, and thermal stability of the ZrO2 films grown on Si(100) were investigated in detail. A 2 nm thick interfacial layer (IL) is formed at the ZrO2–Si interface for the as-grown ZrO2. The optical constants of ZrO2 films and IL correspond to amorphous-ZrO2 and amorphous-SiO2, respectively. The oxidation and IL growth at 900 °C, as a function of annealing time, exhibit a two-step behavior with a slow and a fast growth-rate zones. The transition from a zone of slow to fast rate is attributed to structurally modified ZrO2 facilitating the faster oxygen transport to the ZrO2/Si interface.
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78.66.Nk Insulators
61.72.Cc Kinetics of defect formation and annealing
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

A method to study the crack healing process of glassformers

W. H. Wu, J. L. Zhang, H. W. Zhou, Y. N. Huang, L. Zhang, and X. N. Ying

Appl. Phys. Lett. 92, 011918 (2008); http://dx.doi.org/10.1063/1.2803070 (3 pages) | Cited 4 times

Online Publication Date: 7 January 2008

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A mechanical spectroscopy method of quantitatively monitoring the healing of stress-induced microcracks in small glass samples is described. Whereas the cracks are generated catastrophically at some unpredictable interval below the glass temperature Tg the healing process proves to be highly reproducible and a characteristic temperature for the crack healing process, the temperature of maximum healing rate Tch coincides with Tg.
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81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.M- Structural failure of materials
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition

Temperature dependence of optical constants for InSb films including molten phases

Shuichi Ohkubo, Kazuhiko Aoki, and Daisuke Eto

Appl. Phys. Lett. 92, 011919 (2008); http://dx.doi.org/10.1063/1.2831656 (3 pages) | Cited 8 times

Online Publication Date: 7 January 2008

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We have measured the temperature dependence of optical constants of InSb films including molten phases. It has been found that the optical constants differ between the as-sputtered amorphous and the molten states. Also, the optical constants exhibit the large change associated with the crystalline-to-molten phase transition. In the crystalline states, the extinction coefficient increases as the temperature increases. This temperature dependence can be explained by the decrease of the band gap energy.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
68.55.ag Semiconductors
78.66.Fd III-V semiconductors
64.70.dg Crystallization of specific substances

Temperature dependence of polarized photoluminescence from nonpolar m-plane InGaN multiple quantum wells for blue laser diodes

Masashi Kubota, Kuniyoshi Okamoto, Taketoshi Tanaka, and Hiroaki Ohta

Appl. Phys. Lett. 92, 011920 (2008); http://dx.doi.org/10.1063/1.2824886 (3 pages) | Cited 29 times

Online Publication Date: 7 January 2008

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Polarized photoluminescence (PL) spectra from nonpolar m-plane InGaN multiple quantum wells (MQWs) in blue laser diode wafers fabricated on m-plane GaN substrates were measured as a function of temperature. The polarization ratio (ρ) and the energy difference between the highest and the second highest valence bands estimated from the energy difference between PL peaks (ΔE) increased with increasing InN molar fraction x (or the estimated anisotropic compressive strain along the m-axis εyy) in the MQWs. The values of ρ at 300 K and ΔE were 0.71 and 76 meV for the case of 430 nm PL peak (x = 0.104, εyy = +0.75%) and 0.92 and 123 meV for the case of 485 nm PL peak (x = 0.175, εyy = +1.26%). These results suggest that the preferred stripe direction is the c axis for nonpolar m-plane laser diodes in the region from violet to near green.
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42.55.Px Semiconductor lasers; laser diodes
78.55.Cr III-V semiconductors
78.67.De Quantum wells

Melt dispersion versus diffusive oxidation mechanism for aluminum nanoparticles: Critical experiments and controlling parameters

Valery I. Levitas, Michelle L. Pantoya, and Birce Dikici

Appl. Phys. Lett. 92, 011921 (2008); http://dx.doi.org/10.1063/1.2824392 (3 pages) | Cited 23 times

Online Publication Date: 8 January 2008

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Critical experiments were performed on Al and MoO3 thermites. The diameter and alumina shell thickness of the Al nanoparticles were varied, and flame propagation velocities were measured. The results strongly support the melt-dispersion mechanism and contradict the diffusion oxidation mechanism. The parameters that control the oxidation rate and flame velocity are justified and directions for the synthesis of Al nanoparticles (which are opposite to the current directions based on diffusion oxidation) are suggested. An equation for the flame velocity versus Al nanoparticle geometrical parameters, thermomechanical properties, and synthesis parameters is formulated.
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81.07.Bc Nanocrystalline materials
81.05.Bx Metals, semimetals, and alloys
81.16.Pr Micro- and nano-oxidation
81.65.Mq Oxidation
82.33.Vx Reactions in flames, combustion, and explosions

Light emission due to dislocations in wurtzite ZnO bulk single crystals freshly introduced by plastic deformation

Y. Ohno, H. Koizumi, T. Taishi, I. Yonenaga, K. Fujii, H. Goto, and T. Yao

Appl. Phys. Lett. 92, 011922 (2008); http://dx.doi.org/10.1063/1.2831001 (3 pages) | Cited 6 times

Online Publication Date: 8 January 2008

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An arbitrary number of dislocations were freshly introduced in wurtzite ZnO bulk single crystals by plastic deformation at high temperatures (923–1123 K), and the optical properties were examined by photoluminescence spectroscopy. ZnO, including a high density (more than 109 cm−2) of dislocations, showed excitonic light emission with photon energies of 3.100 and 3.345 eV, as well as their LO-phonon replicas, at a temperature of 11 K, and the intensities increased with increasing dislocation density.
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61.72.Lk Linear defects: dislocations, disclinations
81.40.Lm Deformation, plasticity, and creep
62.20.fq Plasticity and superplasticity
71.35.-y Excitons and related phenomena
78.55.Et II-VI semiconductors

Critical and slow dynamics in a bulk metallic glass exhibiting strong random magnetic anisotropy

Q. Luo, D. Q. Zhao, M. X. Pan, and W. H. Wang

Appl. Phys. Lett. 92, 011923 (2008); http://dx.doi.org/10.1063/1.2827198 (3 pages) | Cited 11 times

Online Publication Date: 9 January 2008

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The nature of the magnetic state of strong random magnetic anisotropy (RMA) remains elusive. It is unclear whether the RMA and the Ising spin glass systems belong to the same class or not. Here, we demonstrate, by investigations of the static, critical, and slow dynamic properties of a Dy-base bulk metallic glass (BMG), the RMA can be classified to a universal class of glass different from Ising spin glass. The results have implication for understanding the connection between RMA and spin glass and the subtle role of anisotropy in the magnetic transition of disorder and frustrated systems. On the other hand, our study has the significance in developing efficient BMGs for functional applications.
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75.30.Gw Magnetic anisotropy
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.50.Lk Spin glasses and other random magnets
75.10.Nr Spin-glass and other random models

Ultrafine-grained titanium of high interstitial contents with a good combination of strength and ductility

W. Xu, X. Wu, D. Sadedin, G. Wellwood, and K. Xia

Appl. Phys. Lett. 92, 011924 (2008); http://dx.doi.org/10.1063/1.2832657 (3 pages) | Cited 12 times

Online Publication Date: 10 January 2008

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A dehydrided Ti powder of very high oxygen content was successfully consolidated using back pressure equal channel angular processing into a fully dense bulk ultrafine-grained Ti showing apparent compressive ductility as well as high true yield and ultimate strengths of 1350 and 1780 MPa, respectively. Interstitial solid solution strengthening contributed to the majority of the increase in strength with additional contribution from ultrafine grains. Significantly, the material also exhibited much improved ductility for such a high interstitial content, thanks probably to the nonequilibrium grain boundaries and bimodal grain structure introduced during severe plastic deformation.
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81.40.Cd Solid solution hardening, precipitation hardening, and dispersion hardening; aging
61.72.Mm Grain and twin boundaries
81.40.Lm Deformation, plasticity, and creep
62.20.fq Plasticity and superplasticity
62.20.fk Ductility, malleability
62.20.fg Shape-memory effect; yield stress; superelasticity
61.72.jj Interstitials

Defect modes merging in one-dimensional photonic crystals with multiple single-negative material defects

Yihang Chen

Appl. Phys. Lett. 92, 011925 (2008); http://dx.doi.org/10.1063/1.2832661 (3 pages) | Cited 12 times

Online Publication Date: 10 January 2008

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Twin defect modes are found to merge into each other in one-dimensional photonic crystals consisting of periodic layers of single-negative (permittivity- or permeability-negative) materials and multiple single-negative defect layers. By increasing the size or the number of the defects, the two defect modes both approach to the middle of the forbidden band gap, then merge when the photonic structure becomes nihility. In addition, the electric fields at the central frequency of the band gap could be designed to be strongly localized at just one interface between the defect layers and the periodic layers of the photonic crystal with low transmission.
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42.70.Qs Photonic bandgap materials
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