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25 Aug 2008

Volume 93, Issue 8, Articles (08xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 93, 083901 (2008); http://dx.doi.org/10.1063/1.2973167 (3 pages)

R. J. Martín-Palma, C. G. Pantano, and A. Lakhtakia
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UV polaritonic emission from a perovskite-based microcavity

G. Lanty, J. S. Lauret, E. Deleporte, S. Bouchoule, and X. Lafosse

Appl. Phys. Lett. 93, 081101 (2008); http://dx.doi.org/10.1063/1.2971206 (3 pages) | Cited 4 times

Online Publication Date: 25 August 2008

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We report on the realization of a molecule-based one-dimensional microcavity emitting in the near UV range at room temperature. The active material is a thin film of the two-dimensional perovskite (C6H5C2H4–NH3)2PbCl4, a molecular compound absorbing and emitting light around 3.6 eV. Angle-resolved reflectivity and photoluminescence measurements show that this microcavity works in the strong coupling regime. The emitting UV polariton is a mixed state between the photon cavity mode and the exciton of the perovskite-type semiconductor.
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78.55.Kz Solid organic materials
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
71.35.-y Excitons and related phenomena

GaNAsSb/GaAs waveguide photodetector with response up to 1.6 μm grown by molecular beam epitaxy

W. K. Loke, S. F. Yoon, Z. Xu, K. H. Tan, T. K. Ng, Y. K. Sim, S. Wicaksono, N. Saadsaoud, D. Decoster, and J. Chazelas

Appl. Phys. Lett. 93, 081102 (2008); http://dx.doi.org/10.1063/1.2976124 (3 pages) | Cited 1 time

Online Publication Date: 25 August 2008

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We present a GaNAsSb/GaAs p-i-n waveguide photodetector operating in the 1.0–1.6 μm wavelength range with enhanced photoresponsivity compared to a top-illuminated photodetector fabricated using the same material system. The device consists of a strained GaNAsSb layer, with N and Sb contents of 3.5% and 18%, respectively, sandwiched between GaAs:Si (n-type) and GaAs:C (p-type) layers. X-ray reciprocal space map of the GaNAsSb layer before device fabrication showed that the film relaxation is ∼ 1%. At 1.55 μm, photoresponsivities of 0.25 and 0.29 A/W for devices with 6.5 and 10 μm ridge width, respectively, was demonstrated.
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85.60.Gz Photodetectors (including infrared and CCD detectors)

Liquid crystal display using combined fringe and in-plane electric fields

Ji Woong Park, Young Joo Ahn, Jun Ho Jung, Seung Hee Lee, Ruibo Lu, Hyang Yul Kim, and Shin-Tson Wu

Appl. Phys. Lett. 93, 081103 (2008); http://dx.doi.org/10.1063/1.2973152 (3 pages) | Cited 11 times

Online Publication Date: 25 August 2008

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A high performance liquid crystal display using combined fringe and in-plane horizontal electric fields is proposed. The strong electric fields cause more liquid crystals to reorient almost in plane above and between the pixel electrodes. As a result, the operation voltage is lower and transmittance is higher than those of fringe field switching and in-plane switching modes, while preserving a wide viewing angle. Such a high performance device is particularly attractive for large panel liquid crystal displays.
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42.79.Kr Display devices, liquid-crystal devices
85.60.Pg Display systems

Extraordinary midinfrared transmission of rectangular coaxial nanoaperture arrays

Ahmet Ali Yanik, Xihua Wang, Shyamsunder Erramilli, Mi K. Hong, and Hatice Altug

Appl. Phys. Lett. 93, 081104 (2008); http://dx.doi.org/10.1063/1.2973165 (3 pages) | Cited 17 times

Online Publication Date: 25 August 2008

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We analyze the extraordinary transmission effect in the periodic and random nanoaperture arrays in optically thick metal films. Experimental studies are combined with simulations to show that extraordinary transmission effect at midinfrared wavelengths is enhanced when the decaying waveguide mode of a single nanoaperture couples through the collective surface plasmon excitations created through periodicity. Transmission characteristics of the individual nanoapertures are investigated by randomizing the apertures. By comparing rectangular to coaxial rectangular nanoapertures, both of which support TE01-like decaying waveguide modes, we study the effect of nanoaperture geometry on the efficiency of the transmission.
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84.40.Az Waveguides, transmission lines, striplines

Unidirectional single-frequency lasing from a ring-spiral coupled microcavity laser

Xiang Wu, Hao Li, Liying Liu, and Lei Xu

Appl. Phys. Lett. 93, 081105 (2008); http://dx.doi.org/10.1063/1.2961025 (3 pages) | Cited 9 times

Online Publication Date: 25 August 2008

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A ring-spiral coupled microcavity laser was fabricated. The ring resonator works as an oscillator and has a diameter that is slightly less than that of the spiral cavity. The spiral provides wavelength selective feedback and emits light out from the notch. As a result, the coupled cavity generates unidirectional single-frequency laser emission. Its lasing threshold is also significantly lower than a single spiral-shaped microcavity laser.
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42.55.Sa Microcavity and microdisk lasers
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.55.Mv Dye lasers
42.60.By Design of specific laser systems
42.70.Hj Laser materials

Photonic crystal fiber microtaper supporting two selective higher-order modes with high sensitivity to gas molecules

D. Monzón-Hernández, Vladimir P. Minkovich, Joel Villatoro, Mark P. Kreuzer, and Gonçal Badenes

Appl. Phys. Lett. 93, 081106 (2008); http://dx.doi.org/10.1063/1.2973641 (3 pages) | Cited 12 times

Online Publication Date: 25 August 2008

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A photonic crystal fiber consisting of three rings of air holes was tapered down to 3–5 μm. The voids of the fiber were collapsed so a solid microtaper was formed. In this microtaper two selective higher-order modes propagate and interfere. This makes the transmission of the taper to exhibit a sinusoidal pattern with subnanometric width fringes. It was found that the device was highly sensitive to gas molecules. The latter is attributed to surface refractive index changes, number of molecules enveloping the taper, and high sensitivity of the modes participating in the interference.
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42.81.Wg Other fiber-optical devices
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
42.70.Qs Photonic bandgap materials

GaSb based light emitting diodes with strained InGaAsSb type I quantum well active regions

Sergey Suchalkin, Seungyong Jung, Gela Kipshidze, Leon Shterengas, Takashi Hosoda, David Westerfeld, Donald Snyder, and Gregory Belenky

Appl. Phys. Lett. 93, 081107 (2008); http://dx.doi.org/10.1063/1.2974795 (3 pages) | Cited 10 times

Online Publication Date: 26 August 2008

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Mid-IR (λ ≈ 3–3.5 μm) light emitting diodes with quinternary AlInGaAsSb barriers and InGaAsSb strained quantum wells grown on GaSb substrates have been demonstrated. The devices produced a quasi-cw emission power of 0.7 mW at room temperature and 2.5 mW at T = 80 K.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Nanoscale epitaxial lateral overgrowth of GaN-based light-emitting diodes on a SiO2 nanorod-array patterned sapphire template

C. H. Chiu, H. H. Yen, C. L. Chao, Z. Y. Li, Peichen Yu, H. C. Kuo, T. C. Lu, S. C. Wang, K. M. Lau, and S. J. Cheng

Appl. Phys. Lett. 93, 081108 (2008); http://dx.doi.org/10.1063/1.2969062 (3 pages) | Cited 33 times

Online Publication Date: 26 August 2008

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High efficiency GaN-based light-emitting diodes (LEDs) are demonstrated by a nanoscale epitaxial lateral overgrowth (NELO) method on a SiO2 nanorod-array patterned sapphire substrate (NAPSS). The transmission electron microscopy images suggest that the voids between SiO2 nanorods and the stacking faults introduced during the NELO of GaN can effectively suppress the threading dislocation density. The output power and external quantum efficiency of the fabricated LED were enhanced by 52% and 56%, respectively, compared to those of a conventional LED. The improvements originated from both the enhanced light extraction assisted by the NAPSS and the reduced dislocation densities using the NELO method.
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85.60.Jb Light-emitting devices
81.05.Ea III-V semiconductors
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.A- Nucleation and growth
68.37.Og High-resolution transmission electron microscopy (HRTEM)

High efficiency operation of butt joint line-defect-waveguide microlaser in two-dimensional photonic crystal slab

Wanhua Zheng, Gang Ren, Mingxin Xing, Wei Chen, Anjin Liu, Wenjun Zhou, Toshihiko Baba, Kango Nozaki, and Lianghui Chen

Appl. Phys. Lett. 93, 081109 (2008); http://dx.doi.org/10.1063/1.2973207 (3 pages) | Cited 2 times

Online Publication Date: 26 August 2008

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Butt joint line-defect-waveguide microlasers are demonstrated on photonic crystal slabs with airholes in a triangular lattice. Such microlaser is designed to increase the output power from the waveguide edge directly. The output power is remarkably enhanced to 214 times higher by introducing chirped structure in the output waveguide. The lasing mode operates in the linear dispersion region of the output waveguide so that the absorption loss due to the band-edge effect is reduced. The laser resonance is illustrated theoretically using the finite difference time domain method. A practical high power efficiency of 20% is obtained in this microlaser.
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42.55.Sa Microcavity and microdisk lasers
42.70.Qs Photonic bandgap materials
02.70.Bf Finite-difference methods

Strain relaxation induced microphotoluminescence characteristics of a single InGaN-based nanopillar fabricated by focused ion beam milling

Peichen Yu, C. H. Chiu, Yuh-Renn Wu, H. H. Yen, J. R. Chen, C. C. Kao, Han-Wei Yang, H. C. Kuo, T. C. Lu, W. Y. Yeh, and S. C. Wang

Appl. Phys. Lett. 93, 081110 (2008); http://dx.doi.org/10.1063/1.2965461 (3 pages) | Cited 3 times

Online Publication Date: 26 August 2008

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A freestanding nanopillar with a diameter of 300 nm and a height of 2 μm is demonstrated by focused ion beam milling. The measured microphotoluminescence (μ-PL) from the embedded InGaN/GaN multiple quantum wells shows a blueshift of 68 meV in energy with a broadened full width at half maximum, ∼ 200 meV. Calculations based on the valence force field method suggest that the spatial variation of the strain tensors in the nanopillar results in the observed energy shift and spectrum broadening. Moreover, the power-dependent μ-PL measurement suggests that the strain-relaxed emission region exhibits a higher radiative recombination rate than that of the strained region, indicating potential for realizing high-efficiency nanodevices in the UV/blue wavelength range.
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81.16.-c Methods of micro- and nanofabrication and processing
78.67.De Quantum wells
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
73.21.Fg Quantum wells
81.07.St Quantum wells

A hybrid green light-emitting diode comprised of n-ZnO/(InGaN/GaN) multi-quantum-wells/p-GaN

C. Bayram, F. Hosseini Teherani, D. J. Rogers, and M. Razeghi

Appl. Phys. Lett. 93, 081111 (2008); http://dx.doi.org/10.1063/1.2975165 (3 pages) | Cited 20 times

Online Publication Date: 27 August 2008

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Hybrid green light-emitting diodes (LEDs) comprised of n-ZnO/(InGaN/GaN) multi-quantum-wells/p-GaN were grown on semi-insulating AlN/sapphire using pulsed laser deposition for the n-ZnO and metal organic chemical vapor deposition for the other layers. X-ray diffraction revealed that high crystallographic quality was preserved after the n-ZnO growth. LEDs showed a turn-on voltage of 2.5 V and a room temperature electroluminescence (EL) centered at 510 nm. A blueshift and narrowing of the EL peak with increasing current was attributed to bandgap renormalization. The results indicate that hybrid LED structures could hold the prospect for the development of green LEDs with superior performance.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Electrical spin injection and optical detection in InAs based light emitting diodes

A. V. Stier, C. J. Meining, B. D. McCombe, I. Chado, P. Grabs, G. Schmidt, and L. W. Molenkamp

Appl. Phys. Lett. 93, 081112 (2008); http://dx.doi.org/10.1063/1.2975170 (3 pages) | Cited 2 times

Online Publication Date: 27 August 2008

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Results of low temperature circularly polarized electroluminescence (EL) studies of InAs-based spin-light emitting diodes in magnetic fields up to 10 T are presented. Spin polarized electrons injected from cubic n-(CdMn)Se recombine with unpolarized holes resulting in emission with a positive degree of optical polarization over this entire magnetic field range. Detailed rate equation modeling of the optical polarization degree (OPD) confirms a high spin injection efficiency (74%–95%) and a spin lifetime τs longer than the optical recombination time τr. Estimates of the temperature dependence of the ratio τr/τs from the OPD are compared with the Elliot–Yafet and Dyakonov–Perel models.
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72.25.Dc Spin polarized transport in semiconductors
72.80.Ey III-V and II-VI semiconductors
78.55.Cr III-V semiconductors
85.60.Jb Light-emitting devices

Dense wavelength conversion and multicasting in a resonance-split silicon microring

Qiang Li, Ziyang Zhang, Fangfei Liu, Min Qiu, and Yikai Su

Appl. Phys. Lett. 93, 081113 (2008); http://dx.doi.org/10.1063/1.2976123 (3 pages) | Cited 5 times

Online Publication Date: 27 August 2008

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We experimentally demonstrate all-optical wavelength conversions in a 10 μm radius resonance-split silicon microring resonator based on free carrier dispersion effect. The split resonance is caused by the mutual coupling between the two countertraveling modes inside the ring resonator. Dense wavelength conversions are performed at data rates from 500 Mbytes/s to 5 Gbytes/s and a dual-channel wavelength multicasting is realized at a data rate of 1.25 Gbytes/s. The resonance splitting phenomenon opens up opportunities to convert more closely spaced wavelengths, thus effectively increasing the system capacity.
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42.82.-m Integrated optics
42.79.Nv Optical frequency converters

Optimized photocathode for spin-polarized electron sources

Yu. A. Mamaev, L. G. Gerchikov, Yu. P. Yashin, D. A. Vasiliev, V. V. Kuzmichev, V. M. Ustinov, A. E. Zhukov, V. S. Mikhrin, and A. P. Vasiliev

Appl. Phys. Lett. 93, 081114 (2008); http://dx.doi.org/10.1063/1.2976437 (3 pages) | Cited 6 times

Online Publication Date: 27 August 2008

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Photocathode for highly polarized electron emission has been developed, fabricated, and studied. The photocathode is based on short-period strained AlInGaAs/AlGaAs superlattice grown by molecular beam epitaxy. Deformation of AlInGaAs quantum well results in 87 meV energy splitting between heavy hole and light hole minibands. Electron emission from the developed photocathode demonstrates maximal polarization of 92% with quantum efficiency of 0.85% at room temperature.
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85.60.Ha Photomultipliers; phototubes and photocathodes

Modulation of single quantum dot energy levels by a surface-acoustic-wave

J. R. Gell, M. B. Ward, R. J. Young, R. M. Stevenson, P. Atkinson, D. Anderson, G. A. C. Jones, D. A. Ritchie, and A. J. Shields

Appl. Phys. Lett. 93, 081115 (2008); http://dx.doi.org/10.1063/1.2976135 (3 pages) | Cited 11 times

Online Publication Date: 28 August 2008

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This letter presents an experimental investigation into the effect of a surface-acoustic-wave (SAW) on the emission of a single InAs quantum dot. The SAW causes the energy of the transitions within the dot to oscillate at the frequency of the SAW, producing a characteristic broadening of the emission lines in their time-averaged spectra. This periodic tuning of the transition energy is used as a method to regulate the output of a device containing a single quantum dot and we study the system as a high-frequency periodic source of single photons.
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73.21.La Quantum dots
68.35.Iv Acoustical properties

Indium incorporation dynamics into AlInN ternary alloys for laser structures lattice matched to GaN

H. P. D. Schenk, M. Nemoz, M. Korytov, P. Vennéguès, A. D. Dräger, and A. Hangleiter

Appl. Phys. Lett. 93, 081116 (2008); http://dx.doi.org/10.1063/1.2971027 (3 pages) | Cited 15 times

Online Publication Date: 29 August 2008

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Al1−xInxN ternary alloys with solid phase indium compositions between x = 0.15 and 0.28 have been grown by metal organic chemical vapor deposition under indium rich conditions within the growth temperature range of 750–810 °C. A thermally activated process with activation energy of 1.05±0.05 eV is found to compete with indium incorporation. Smooth epitaxial layers with root mean-squares surface roughness of 0.3–0.8 nm are obtained. (Al,In)N films lattice matched to GaN have been introduced into laser diode structures for optical confinement. Optical gain is observed.
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81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.ag Semiconductors
68.35.bg Semiconductors
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems

Tunable lasers on GaSb using the concept of binary superimposed gratings

M. Müller, T. Lehnhardt, K. Rößner, and A. Forchel

Appl. Phys. Lett. 93, 081117 (2008); http://dx.doi.org/10.1063/1.2977461 (3 pages) | Cited 2 times

Online Publication Date: 29 August 2008

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We report the realization of widely tunable single-mode emitting laser diodes on the (AlGaIn)/(AsSb) material system employing binary superimposed gratings. Through this specialized concept of multifrequency selective gratings, it is possible to generate a tunable laser emitting at several predetermined wavelengths. One major advantage of this approach is the simple fabrication process, which is similar to standard distributed feedback fabrication technologies, but with the result of one single laser emitting single mode at several discrete emission wavelengths.
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42.55.Px Semiconductor lasers; laser diodes
42.79.Dj Gratings
42.60.Fc Modulation, tuning, and mode locking

High output power GaN-based light-emitting diodes using an electrically reverse-connected p-Schottky diode and p-InGaN–GaN superlattice

Ja-Soon Jang

Appl. Phys. Lett. 93, 081118 (2008); http://dx.doi.org/10.1063/1.2977471 (3 pages) | Cited 10 times

Online Publication Date: 29 August 2008

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We demonstrate the high-performance and excellent reliability characteristics of InGaN–GaN light-emitting diodes (LEDs) using an electrically reverse-connected p-Schottky diode and p-InGaN–GaN superlattice (SL). Measurements show that the LED with the Schottky diode and SL yields lower series resistance and higher output power compared to normal LEDs. In addition, the device degradation rate of the proposed LED is 33 times as low as that of the normal LED at high electrical stress of 410 A/cm2, indicating excellent reliability behavior. These results mean that the use of p-Schottky diode and p-SL is very promising for the realization of high-performance GaN-based LEDs.
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68.65.Cd Superlattices
85.60.Jb Light-emitting devices
85.30.Kk Junction diodes
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Spectrum modulation of relativistic electrons by laser wakefield

N. Nakanii, K. Kondo, Y. Kuramitsu, Y. Mori, E. Miura, K. Tsuji, K. Kimura, S. Fukumochi, M. Kashihara, T. Tanimoto, H. Nakamura, T. Ishikura, K. Takeda, M. Tampo, H. Takabe, et al.

Appl. Phys. Lett. 93, 081501 (2008); http://dx.doi.org/10.1063/1.2971235 (3 pages) | Cited 1 time

Online Publication Date: 25 August 2008

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Energetic electrons were generated by the interaction of a high-intensity laser pulse with a plasma preformed from a hollow plastic cylinder via laser-driven implosion. The spectra of a comparatively high-density plasma ∼ 1019 cm−3 had a bump around 10 MeV. Simple numerical calculations explained the spectra obtained in this experiment. This indicates that the plasma tube has sufficient potential to convert a Maxwellian spectrum to a comparatively narrow spectrum.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.38.Dx Laser light absorption in plasmas (collisional, parametric, etc.)

The role of the relative voltage and phase for frequency coupling in a dual-frequency capacitively coupled plasma

D. O’Connell, T. Gans, E. Semmler, and P. Awakowicz

Appl. Phys. Lett. 93, 081502 (2008); http://dx.doi.org/10.1063/1.2972117 (3 pages) | Cited 13 times

Online Publication Date: 25 August 2008

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Frequency coupling in multifrequency discharges is a complex nonlinear interaction of the different frequency components. An alpha-mode low pressure rf capacitively coupled plasma operated simultaneously with two frequencies is investigated and the coupling of the two frequencies is observed to greatly influence the excitation and ionization within the discharge. Through this, plasma production and sustainment are dictated by the corresponding electron dynamics and can be manipulated through the dual-frequency sheath. These mechanisms are influenced by the relative voltage and also the relative phase of the two frequencies.
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52.80.Pi High-frequency and RF discharges
52.50.-b Plasma production and heating
52.40.Kh Plasma sheaths
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.35.Mw Nonlinear phenomena: waves, wave propagation, and other interactions (including parametric effects, mode coupling, ponderomotive effects, etc.)

Plasma characterization in a diode with a carbon-fiber cathode

V. Vekselman, J. Gleizer, D. Yarmolich, J. Felsteiner, Ya. Krasik, L. Liu, and V. Bernshtam

Appl. Phys. Lett. 93, 081503 (2008); http://dx.doi.org/10.1063/1.2976136 (3 pages) | Cited 7 times

Online Publication Date: 25 August 2008

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Results of optical and spectroscopic studies of the plasma formation at the surface of two types of carbon-fiber cathodes in a diode powered by an ∼ 200 kV accelerating pulse are presented. It was found that during the pulse, generation of the plasma occurs in a form of several millimeter size plasma spots. In the vicinity of the cathode surface the average plasma density and temperature were found to be ∼ 3×1014 cm−3 and ∼ 5 eV, respectively, for an electron current density of ∼ 22 A/cm2. The plasma expansion velocity toward the anode was found to be ∼ 1.5×106 cm/s during the first 150 ns of the accelerating pulse duration.
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52.75.Fk Magnetohydrodynamic generators and thermionic convertors; plasma diodes
52.70.-m Plasma diagnostic techniques and instrumentation
52.25.-b Plasma properties

Temperature-dependent transition of discharge pattern of He/air cryoplasma

Jai Hyuk Choi, Yuri Noma, Takaaki Tomai, and Kazuo Terashima

Appl. Phys. Lett. 93, 081504 (2008); http://dx.doi.org/10.1063/1.2976308 (3 pages) | Cited 7 times

Online Publication Date: 26 August 2008

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Dielectric barrier discharges were generated under atmospheric pressure at temperatures ranging from room temperature down to 88 K. The gas temperature of the plasma generated by the discharges was controlled by liquid nitrogen, and a mixture of helium and air was used as the discharge gas. We found that microdischarges exhibited temperature-dependent specific discharge patterns as the temperature decreased. This transition of discharge patterns was closely related to the change in the gap voltage at breakdown. A possible scenario that may explain the pattern of the transition of the microdischarges is discussed.
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52.25.-b Plasma properties
52.80.-s Electric discharges
52.50.Dg Plasma sources
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
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Investigation of the nanomechanical properties in relation to the microstructure of Zn1−xBexTe alloys

S. E. Grillo, H. Glénat, T. Tite, O. Pages, O. Maksimov, and M. C. Tamargo

Appl. Phys. Lett. 93, 081901 (2008); http://dx.doi.org/10.1063/1.2970989 (3 pages) | Cited 2 times

Online Publication Date: 25 August 2008

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A study by nanoindentation has been performed to investigate the variation of the mechanical properties of Zn1−xBexTe alloys as a function of the beryllium content in the range 0 ≤ x ≤ 0.84. Our data show a very marked increase of hardness (H) and a significant increase of the elastic modulus (E) with Be concentration. These trends are related to an increase in the stiffness of the BeTe bond relative to that of the ZnTe bond. Furthermore, discontinuities are unambiguously revealed in the variations of both H and E at the critical Be content of ∼ 20%. We relate these to Raman studies of the layers’ microstructure and propose an explanation in terms of a percolative behavior.
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81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.dq Other elastic constants
62.20.de Elastic moduli
78.30.Er Solid metals and alloys

Low-temperature negative thermal expansion of the antiperovskite manganese nitride Mn3CuN codoped with Ge and Si

Rongjin Huang, Laifeng Li, Fangshuo Cai, Xiangdong Xu, and Lihe Qian

Appl. Phys. Lett. 93, 081902 (2008); http://dx.doi.org/10.1063/1.2970998 (3 pages) | Cited 29 times

Online Publication Date: 25 August 2008

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We have synthesized antiperovskite manganese nitrides Mn3(Cu0.6SixGe0.4−x)N, (x = 0–0.2) and investigated their negative thermal expansion (NTE) in the temperature range of 80–300 K. We found that the transition temperature of NTE moves toward lower temperature region and as well the NTE operation-temperature window (ΔT) becomes broader with increasing Si content. Typically, the giant low-temperature NTE coefficient identified in Mn3(Cu0.6Si0.15Ge0.25)N reaches as large as −16×10−6 K−1, and its ΔT reaches as wide as 100 K. The magnetic properties of these compounds were measured and correlated with the broadened NTE operation-temperature window. The present discovery highlights the potential applications of NTE materials in cryogenic engineering.
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65.40.De Thermal expansion; thermomechanical effects
75.30.Cr Saturation moments and magnetic susceptibilities
75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
75.80.+q Magnetomechanical effects, magnetostriction

Phase transformations during rapid heating of Al/Ni multilayer foils

Jonathan C. Trenkle, Lucas J. Koerner, Mark W. Tate, Sol M. Gruner, Timothy P. Weihs, and Todd C. Hufnagel

Appl. Phys. Lett. 93, 081903 (2008); http://dx.doi.org/10.1063/1.2975830 (3 pages) | Cited 17 times

Online Publication Date: 25 August 2008

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We have used self-propagating exothermic reactions in Al/Ni multilayers as a means to explore the effect of rapid heating on phase transformations. Using time-resolved synchrotron x-ray microdiffraction with an extremely fast detector, we were able to examine the reaction sequence in detail at heating rates of ∼ 106 K s−1. We observed that the intermediate phases formed during the self-propagating reactions are different from those formed at lower heating rates, even though the final phases are the same. In situ characterization is essential, as other means of studying self-propagating reactions (such as quenching the reaction followed by ex situ analysis) provide different—and potentially misleading—results.
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64.70.kd Metals and alloys
81.40.Gh Other heat and thermomechanical treatments
68.65.Ac Multilayers
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  1. Morphological and chemical optimization of ex situ NH4F (40%) conditioned Si(111)-(1×1):H
  2. A study of metal-oxide-semiconductor capacitors on GaAs, In0.53Ga0.47As, InAs, and InSb substrates using a germanium interfacial passivation layer
  3. Amplification of transition-Cherenkov terahertz radiation of femtosecond filament in air
  4. Laser microfabrication and rotation of ship-in-a-bottle optical rotators
  5. Analytical model of spin-polarized semiconductor lasers
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