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21 Apr 2008

Volume 92, Issue 16, Articles (16xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 92, 162501 (2008); http://dx.doi.org/10.1063/1.2909581 (3 pages)

J. J. Kim, K. Hirata, Y. Ishida, D. Shindo, M. Takahashi, and A. Tonomura
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Hole confinement in quantum islands in Ga(AsSb)/GaAs/(AlGa)As heterostructures

S. Horst, S. Chatterjee, K. Hantke, P. J. Klar, I. Nemeth, W. Stolz, K. Volz, C. Bückers, A. Thränhardt, S. W. Koch, W. Rühle, S. R. Johnson, J.-B. Wang, and Y.-H. Zhang

Appl. Phys. Lett. 92, 161101 (2008); http://dx.doi.org/10.1063/1.2913767 (3 pages) | Cited 3 times

Online Publication Date: 21 April 2008

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Formation of self-organized Ga(AsSb) quantum islands during growth is shown to occur in a series of Ga(AsSb)/GaAs/(AlGa)As heterostructures, resulting in an in-plane hole confinement of several hundred meV. The shape of the in-plane confinement potential is nearly parabolic and, thus, yields almost equidistant hole energy levels. Transmission electron microscopy reveals that the quantum islands are 100 nm in diameter and exhibit an in-plane variation of the Sb concentration of more than 30%. Up to seven bound hole states are observed in the photoluminescence spectra. Time-resolved photoluminescence data are shown as function of excitation density, lattice temperature, and excitation photon energy and reveal fast carrier capture into, and relaxation within, the quantum islands. The advantages of such structures as active laser material are discussed.
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78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
73.21.La Quantum dots

Low-loss terahertz transmission through curved metallic slit waveguides fabricated by spark erosion

Markus Wächter, Michael Nagel, and Heinrich Kurz

Appl. Phys. Lett. 92, 161102 (2008); http://dx.doi.org/10.1063/1.2913006 (3 pages) | Cited 4 times

Online Publication Date: 21 April 2008

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Propagation characteristics of broadband terahertz pulses in straight and curved metallic slit (MS) waveguides fabricated using spark erosion technique are investigated in the 0.1–1.0 THz frequency range. As the straight MS waveguides, the curved MS waveguides, having radii of curvature as small as 5 mm, exhibit comparably undistorted terahertz pulse transmission. The observed bending loss is unexpectedly low, giving rise to the assumption that surface oxidization and roughness generated by the fabrication process are responsible for the improved signal routing behavior. Experimental results are compared with theoretical data from numerical field simulations incorporating the influence of a thin dielectric cover layer.
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84.40.Az Waveguides, transmission lines, striplines
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

Long-range surface plasmon polaritons on asymmetric double-electrode structures

Yang Hyun Joo, Myoung Jin Jung, Jaewoong Yoon, Seok Ho Song, Hyong Sik Won, Suntak Park, and Jung Jin Ju

Appl. Phys. Lett. 92, 161103 (2008); http://dx.doi.org/10.1063/1.2913015 (3 pages) | Cited 10 times

Online Publication Date: 21 April 2008

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An asymmetric double-electrode structure composed of metal strips separated by a dielectric core layer, all on a metal slab, is proposed as a long-range surface plasmon-polariton (LR-SPP) waveguide. LR-SPP modes on asymmetric structures, including straight, S-bended, and Y-branched strips, are found by far-field measurement to be consistent with theoretical estimates. The proposed structure is inherently free from a symmetry requirement on dielectric constants between the core and cladding materials, therefore, an asymmetric double-electrode waveguide which substitutes a nonlinear medium or biofluid for the core dielectric may be essential to realization of SPP nonlinear devices or biosensors in a long-range manner.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
42.65.Wi Nonlinear waveguides
77.22.Ch Permittivity (dielectric function)
78.66.Bz Metals and metallic alloys

Exciton dynamics in current-injected single quantum dot at 1.55 μm

Toshiyuki Miyazawa, Toshihiro Nakaoka, Tatsuya Usuki, Yasuhiko Arakawa, Kazuya Takemoto, Shinnichi Hirose, Shigekazu Okumura, Motomu Takatsu, and Naoki Yokoyama

Appl. Phys. Lett. 92, 161104 (2008); http://dx.doi.org/10.1063/1.2909556 (3 pages) | Cited 7 times

Online Publication Date: 21 April 2008

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We investigate the exciton dynamics in a current-injected single InAs quantum dot (QD) which emits 1.55 μm photons. Photon antibunching behavior is observed using a single electroluminescence line of a single QD. The radiative lifetime of this line determined by time-resolved measurement is 1.59 ns. The single exciton recombination time agrees with the lifetime calculated with an eight-band kp model. We examine a high drive rate operation of the device by changing the delay time between two electrical pulses. These results demonstrate that our device has the potential to achieve telecommunication band subgigahertz single-photon emission with electrical pulses.
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78.47.jd Time resolved luminescence
71.35.-y Excitons and related phenomena
73.21.La Quantum dots
78.60.Fi Electroluminescence
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Intraband emission at λ ≈ 1.48 μm from GaN/AlN quantum dots at room temperature

L. Nevou, F. H. Julien, M. Tchernycheva, F. Guillot, E. Monroy, and E. Sarigiannidou

Appl. Phys. Lett. 92, 161105 (2008); http://dx.doi.org/10.1063/1.2913756 (3 pages) | Cited 9 times

Online Publication Date: 22 April 2008

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We report on the intraband emission at room temperature from GaN/AlN quantum dots grown by plasma-assisted molecular-beam epitaxy. The dots exhibit TM-polarized absorption ascribed to the intraband transition from the s to the pz shells. The pz-s intraband luminescence is observed at λ = 1.48 μm under optical excitation at λ = 1.34 μm perpendicular to the [0001] growth axis. The population of the pz state arises from Raman scattering by GaN A1 longitudinal optical phonons. Based on the emission spectral shape, we estimate that the homogeneous linewidth of the s-pz intraband transition is less than 4 meV.
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78.67.Hc Quantum dots
78.55.Cr III-V semiconductors
78.30.Fs III-V and II-VI semiconductors
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials

Two-photon excited luminescence spectral distribution observation in wide-gap semiconductor crystals

A. S. M. Noor, A. Miyakawa, Y. Kawata, and M. Torizawa

Appl. Phys. Lett. 92, 161106 (2008); http://dx.doi.org/10.1063/1.2913760 (2 pages) | Cited 1 time

Online Publication Date: 22 April 2008

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The use of photoluminescence excited with two-photon process for characterizing the defect and impurity level in wide-gap semiconductor is discussed in this paper. Defects of polycrystalline zinc selenide (ZnSe) is observed deep inside the crystal. Two types of defects can be detected based on the spectral luminescence image. One type of defect can be seen in the entire spectrum images. Meanwhile, other types of defects can only be observed at higher energy of the spectrum, from 460 to 465 nm. This study represents works of identifying crystals defect in wide gap materials by two-photon luminescence technique.
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78.55.Et II-VI semiconductors
71.55.Gs II-VI semiconductors
71.20.Nr Semiconductor compounds

Enhanced light emission in photonic crystal nanocavities with Erbium-doped silicon nanocrystals

Maria Makarova, Vanessa Sih, Joe Warga, Rui Li, Luca Dal Negro, and Jelena Vuckovic

Appl. Phys. Lett. 92, 161107 (2008); http://dx.doi.org/10.1063/1.2916711 (3 pages) | Cited 22 times

Online Publication Date: 22 April 2008

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Photonic crystal nanocavities are fabricated in silicon membranes covered by thermally annealed silicon-rich nitride films with Erbium-doped silicon nanocrystals. Silicon nitride films were deposited by sputtering on top of silicon on insulator wafers. The nanocavities were carefully designed in order to enhance emission from the nanocrystal sensitized Erbium at the 1540 nm wavelength. Experimentally measured quality factors of ∼ 6000 were found to be consistent theoretical predictions. The Purcell factor of 1.4 was estimated from the observed 20-fold enhancement of Erbium luminescence.
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78.55.Ap Elemental semiconductors
81.15.Cd Deposition by sputtering
81.16.-c Methods of micro- and nanofabrication and processing
81.07.Bc Nanocrystalline materials
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

Silicon light emitting diodes emitting over the 1.2–1.4 μm wavelength region in the extended optical communication band

M. A. Lourenço, R. M. Gwilliam, and K. P. Homewood

Appl. Phys. Lett. 92, 161108 (2008); http://dx.doi.org/10.1063/1.2916824 (3 pages) | Cited 4 times

Online Publication Date: 22 April 2008

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Here, we demonstrate bulk silicon light emitting diodes operating over the 1.2–1.35 μm range. This is achieved by the implantation of the rare earth thulium, incorporated in the trivalent Tm3+ state, into silicon p-n junctions. Light emitting diodes operating under forward bias have been obtained by codoping of boron to reduce the thermal quenching. Seven sharp lines are observed, corresponding to known internal Tm3+ transitions in the manifold from the 3H5 to the 3H6 ground states. This center, together with the basic 1.15 μm silicon emitters and Si:Er devices operating at 1.54 μm, now enables significant coverage of the extended (1.1–1.8 μm) optical communications band in silicon.
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85.60.Jb Light-emitting devices
42.79.Sz Optical communication systems, multiplexers, and demultiplexers

Effect of pressure on the properties of phosphorus-doped p-type ZnO thin films grown by radio frequency-magnetron sputtering

Dae-Kue Hwang, Min-Suk Oh, Yong-Seok Choi, and Seong-Ju Park

Appl. Phys. Lett. 92, 161109 (2008); http://dx.doi.org/10.1063/1.2913011 (3 pages) | Cited 18 times

Online Publication Date: 22 April 2008

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We report the effect of pressure on the surface morphology, electrical and optical properties of phosphorus (P)-doped p-type ZnO grown by radio frequency magnetron sputtering. The nanorod structures of P-doped ZnO films became dense and flat with decreasing pressure. The Hall effect measurement of the films grown at a pressure of 5–20 mTorr showed an n-type conductivity after rapid thermal annealing. However, the films grown at a low pressure of 1 mTorr showed a p-type conductivity with a hole concentration of 4.71×1818/cm3. This result showed that the pressure of rf-magnetron sputtering plays a critical role in the growth of P-doped p-type ZnO.
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81.15.Cd Deposition by sputtering
68.55.ag Semiconductors
73.61.Ga II-VI semiconductors
78.66.Hf II-VI semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters

Static optical sorting in a laser interference field

Petr Jákl, Tomáš Čižmár, Mojmír Šerý, and Pavel Zemánek

Appl. Phys. Lett. 92, 161110 (2008); http://dx.doi.org/10.1063/1.2913759 (3 pages) | Cited 16 times

Online Publication Date: 24 April 2008

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We present a unique technique for optical sorting of heterogeneous suspensions of microparticles, which does not require the flow of the immersion medium. The method employs the size-dependent response of suspended dielectric particles to the optical field of three intersecting beams that form a fringelike interference pattern. We experimentally demonstrate sorting of a polydisperse suspension of polystyrene beads of diameters 1, 2, and 5.2 μm and living yeast cells.
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42.50.Wk Mechanical effects of light on material media, microstructures and particles
87.17.-d Cell processes
82.70.Kj Emulsions and suspensions

Quantitative force mapping of an optical vortex trap

Yiqiong Zhao, Graham Milne, J. Scott Edgar, Gavin D. M. Jeffries, David McGloin, and Daniel T. Chiu

Appl. Phys. Lett. 92, 161111 (2008); http://dx.doi.org/10.1063/1.2912031 (3 pages) | Cited 7 times

Online Publication Date: 24 April 2008

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This paper describes the quantitative force mapping of micron-sized particles held in an optical vortex trap. We present a simple and efficient model, which accounts for the diffraction of the strongly localized optical field of the tightly focused laser beam, the spherical aberration introduced by the dielectric glass-to-water interface, employs the multidipole approximation for force calculations, and is able to reproduce, with quantitative agreement, the experimentally measured force map.
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42.50.Wk Mechanical effects of light on material media, microstructures and particles
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation

Interaction between the intrinsic second- and third-order optical fields in an Al0.53Ga0.47N/GaN heterostructure

P. Chen, Y. H. Zuo, X. G. Tu, D. J. Cai, S. P. Li, J. Y. Kang, Y. D. Yu, J. Z. Yu, and Q. M. Wang

Appl. Phys. Lett. 92, 161112 (2008); http://dx.doi.org/10.1063/1.2918449 (3 pages)

Online Publication Date: 25 April 2008

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We present an experimental demonstration of the interaction between the intrinsic second- and third-order optical fields in an Al0.53Ga0.47N/GaN heterostructure. The sample was deposited by metal-organic chemical vapor deposition on (0001) sapphire. The nonlinear optical coefficients of the sample, which were measured with a Mach–Zehnder interferometer system, quadratically increase with the applied modulating voltage, indicating the existence of the third-order optical field. The third-order signal was then detected by the Z-scan method and we calculated the built-in dc field on the AlGaN/GaN interface to confirm the strong interaction between the intrinsic second- and third-order optical fields.
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78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
42.65.-k Nonlinear optics

Enhancing the quantum efficiency of InGaN green light-emitting diodes by trimethylindium treatment

Hung-Cheng Lin, Ruo-Syuan Lin, and Jen-Inn Chyi

Appl. Phys. Lett. 92, 161113 (2008); http://dx.doi.org/10.1063/1.2909551 (3 pages) | Cited 11 times

Online Publication Date: 25 April 2008

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This work demonstrates the effectiveness of using trimethylindium (TMIn) treatment to improve the luminescence efficiency of InGaN/GaN quantum wells grown by metal-organic vapor-phase epitaxy. Photoluminescence, x-ray diffraction, atomic force microscopy, and high-resolution transmission electron microscopy indicate that the treatment leads to a smoother InGaN surface and InGaN/GaN interface with substantial decrease in V-shape defects density, compared to the samples without treatment. Green light-emitting diodes prepared by this method exhibit higher output power than the control device. These improvements are attributed to the surface smoothing process in TMIn ambient, resulting in an abrupt InGaN/GaN interface.
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85.60.Jb Light-emitting devices
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
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Generation of hard x rays by femtosecond laser pulse interaction with Cu in laminar helium flow in ambient air

Bixue Hou, James Easter, Karl Krushelnick, and John A. Nees

Appl. Phys. Lett. 92, 161501 (2008); http://dx.doi.org/10.1063/1.2917442 (3 pages) | Cited 5 times

Online Publication Date: 25 April 2008

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Hard x rays are generated in laminar helium flow in atmosphere (without a vacuum vessel) through the interaction of tightly focused 35 fs laser pulses of varying energy with a Cu target. The energy conversion efficiency from laser to Kα x rays is measured to be 5.4×10−6, giving a flux of 5.9×109 photons/s into 2π sr from a source measuring approximately 9×12 μm2 in size (vertical×horizontal). Results are compared to those measured in vacuum and in static helium environments.
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52.59.Px Hard X-ray sources
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.38.Ph X-ray, γ-ray, and particle generation
52.70.La X-ray and γ-ray measurements
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Low-temperature phase separation in GaN nanowires: An in situ x-ray investigation

S. Y. Wu, J.-Y. Ji, M. H. Chou, W.-H. Li, and G. C. Chi

Appl. Phys. Lett. 92, 161901 (2008); http://dx.doi.org/10.1063/1.2913207 (3 pages) | Cited 1 time

Online Publication Date: 21 April 2008

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In this study, we in situ employed low-temperature x-ray diffraction to investigate phase separation in GaN nanowires. Our observations showed that a distinct phase separation developed below 260 K, the zinc-blende phase, which is related to short range ordering. The correlation lengths of the zinc-blende phase reached their maximum at 140 K but correlation length was still revealed at around 23 nm. Our results may be understood using the finite size model and support the conclusion that the phase separation was reversible and occurred through the interaction of the characteristic size of the ordered domain of the GaN nanowires.
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64.75.Jk Phase separation and segregation in nanoscale systems
61.46.Km Structure of nanowires and nanorods (long, free or loosely attached, quantum wires and quantum rods, but not gate-isolated embedded quantum wires)

Defect structure of highly Zn-doped LiNbO3 single crystal revealed by extended x-ray absorption spectra

P.-C. Tsai, M.-L. Sun, C.-T. Chia, H.-F. Lu, S.-H. Lin, M.-L. Hu, and J.-F. Lee

Appl. Phys. Lett. 92, 161902 (2008); http://dx.doi.org/10.1063/1.2913012 (3 pages) | Cited 3 times

Online Publication Date: 22 April 2008

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To determine the defect structure of ZnO-doped LiNbO3 single crystals with high doping concentrations, we obtain the measurements using the extended x-ray absorption fine structure (EXAFS) at room temperature. It indicates Zn atom is directly substituted on the Li site of the LiNbO3 crystal after Zn doping. EXAFS simulation by way of analyzing the scattering amplitudes also shows that the Zn atom does not substitute the Nb site at highly Zn-doped LiNbO3. Finally, we confirm that VNb5−, a strong charged vacancy, should be considered as an important factors in influencing the physical properties of LiNbO3 beyond 7.5 mol % Zn-doped doping concentration.
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61.72.jd Vacancies
61.72.U- Doping and impurity implantation
61.50.-f Structure of bulk crystals
78.70.Dm X-ray absorption spectra

Influence of interlayer magnetostatic coupling on the ferromagnetic resonance properties of lithographically patterned ferromagnetic trilayers

Y. Nozaki, K. Tateishi, S. Taharazako, S. Yoshimura, and K. Matsuyama

Appl. Phys. Lett. 92, 161903 (2008); http://dx.doi.org/10.1063/1.2910724 (3 pages) | Cited 3 times

Online Publication Date: 23 April 2008

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The influence of magnetostatic coupling in a Ni81Fe19/Cu/Ni81Fe19 elliptical element on the ferromagnetic resonance (FMR) properties was experimentally and numerically investigated. Discontinuous variations in the FMR frequencies were observed when the relative orientation of magnetization was switched between parallel and antiparallel. Furthermore, the trilayer element exhibits field-insensitive FMR properties for magnetization of antiparallel orientation. This is attributable to the conflicted magnetic field dependence of the FMR frequency in the top and bottom Ni81Fe19 layers with antiparallel magnetization.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance

Nanoindentation hardness anisotropy of alumina crystal: A molecular dynamics study

Kenji Nishimura, Rajiv K. Kalia, Aiichiro Nakano, and Priya Vashishta

Appl. Phys. Lett. 92, 161904 (2008); http://dx.doi.org/10.1063/1.2913016 (3 pages) | Cited 9 times

Online Publication Date: 23 April 2008

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Atomistic mechanisms of the initial stage of plasticity during nanoindentation are studied by molecular dynamics simulations for three surface orientations of alumina crystal. The simulations predict significant anisotropy and indentation depth dependence of the hardness value at the nanometer scale. The nanohardness anisotropy is found to arise from orientation-dependent dislocation activities. In the (0001) basal plane indentation, prism dislocations are emitted, followed by basal and pyramidal dislocations, to form massive subsurface defects; prism and pyramidal dislocations are emitted on (01math0) and (2mathmath0) prism plane indentations, respectively, to cause modest deformations. Stacking faults are also observed because these dislocations are extended to Shockley partial dislocations.
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68.35.Gy Mechanical properties; surface strains
81.40.Lm Deformation, plasticity, and creep
61.72.Bb Theories and models of crystal defects
61.43.Bn Structural modeling: serial-addition models, computer simulation
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness

Understanding nanoscale damage at a crack tip of multilayered metallic composites

X. F. Zhu, Y. P. Li, G. P. Zhang, J. Tan, and Y. Liu

Appl. Phys. Lett. 92, 161905 (2008); http://dx.doi.org/10.1063/1.2913155 (3 pages) | Cited 8 times

Online Publication Date: 24 April 2008

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Through quantitative focused ion beam cross-sectional characterization technique, we directly observed shear displacement in a range from several nanometers to a few tens of nanometers occurring in the plastic deformation zone ahead of a crack tip in nanolayered Cu/Ta composite subjected to tensile load. As a result, shear-mode fracture of the Cu/Ta laminate composite was eventually caused. A theoretical analysis of the interface barrier strength of nanolayered metallic composites here and reported in literature finds a critical individual layer thickness below which the nature of fracture of the nanolayered composites tends to be shearing failure.
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62.20.mt Cracks
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
61.46.-w Structure of nanoscale materials
62.20.fq Plasticity and superplasticity
81.40.Lm Deformation, plasticity, and creep
68.65.Ac Multilayers
62.20.mm Fracture
62.25.Mn Fracture/brittleness

High internal quantum efficiency ZnO nanorods prepared at low temperature

Jie Chen, L. Aé, Ch. Aichele, and M. Ch. Lux-Steiner

Appl. Phys. Lett. 92, 161906 (2008); http://dx.doi.org/10.1063/1.2910769 (3 pages) | Cited 9 times

Online Publication Date: 25 April 2008

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A preparation process for ZnO nanorods (or nanowires) by use of electrochemical deposition in an aqueous solution of zinc nitrate and nitric acid at temperatures 75 °C was established. The surface morphologies of ZnO nanostructures can be adjusted with constant high internal quantum efficiency (IQE). The as-grown ZnO nanostructures exhibit a dominant and intense near-band-edge emission. The ZnO nanostructures present an IQE of ∼ 28% measured by a He–Cd laser under excitation power density of ∼ 22 W/cm2 at a wavelength of 325 nm.
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81.05.Dz II-VI semiconductors
81.07.Vb Quantum wires
81.16.-c Methods of micro- and nanofabrication and processing
81.15.Pq Electrodeposition, electroplating
82.45.Aa Electrochemical synthesis
78.55.Et II-VI semiconductors

Thermally stable thermoelectric Zn4Sb3 by zone-melting synthesis

B. L. Pedersen and B. B. Iversen

Appl. Phys. Lett. 92, 161907 (2008); http://dx.doi.org/10.1063/1.2916705 (3 pages) | Cited 22 times

Online Publication Date: 25 April 2008

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The thermal stability of thermoelectric Zn4Sb3 has been investigated on samples produced by a new zone-melting technique, as well as by the conventional quench method. The multitemperature synchrotron powder diffraction data reveal that while conventionally synthesized, Zn4Sb3 samples have almost 40% degradation in the first heating cycle at 625 K, samples prepared by zone melting only have 3% degradation. Repeated thermal cycling induces additional degradation of the quenched sample of up to 58%, compared to ∼ 9% degradation in the zone-melted sample. Thus, zone-melting produces Zn4Sb3 samples that are significantly more thermally stable, which make them promising for commercial implementation.
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72.20.Pa Thermoelectric and thermomagnetic effects
81.10.Fq Growth from melts; zone melting and refining
81.40.Gh Other heat and thermomechanical treatments

Scanning confocal fluorescence imaging and micro-Raman investigations of oxygen implanted channel waveguides in Nd:MgO:LiNbO3

D. Jaque, Feng Chen, and Yang Tan

Appl. Phys. Lett. 92, 161908 (2008); http://dx.doi.org/10.1063/1.2917440 (3 pages) | Cited 17 times

Online Publication Date: 25 April 2008

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The spatial variation of the spectroscopic properties of Nd3+ ions in oxygen implanted Nd:MgO:LiNbO3 channel waveguides have been investigated by scanning confocal microluminescence experiments. Although the radiative probabilities of Nd3+ ions were unaffected by the waveguide fabrication procedure, slight changes (in terms of spectral position and width of the emission lines) have been found in the electronic damage region. Raman spectra have been also analyzed in order to get a further understanding on the possible relation of these spectral changes with the micro-modifications induced during the waveguide formation.
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84.40.Az Waveguides, transmission lines, striplines
85.60.-q Optoelectronic devices

Magnetostriction in Mn3CuN

K. Asano, K. Koyama, and K. Takenaka

Appl. Phys. Lett. 92, 161909 (2008); http://dx.doi.org/10.1063/1.2917472 (3 pages) | Cited 39 times

Online Publication Date: 25 April 2008

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Discovery of large magnetostriction in an antiperovskite Mn3CuN is reported. Mn3CuN undergoes the first-order transition from high-temperature (high-T) paramagnetic to low-temperature ferromagnetic (FM) phase at the Curie temperature TC = 143 K, accompanied by cubic-to-tetragonal structural deformation. In the tetragonally distorted FM phase, Mn3CuN, even in a polycrystalline form, expands 0.2% and shrinks 0.1% in the direction parallel and perpendicular to the external field of 90 kOe, respectively. This magnetostriction is possibly due to rearrangement of thermoelastic martensite variants by magnetic field, similar to FM Heusler alloys such as Ni2MnGa.
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75.80.+q Magnetomechanical effects, magnetostriction
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.40.-s Critical-point effects, specific heats, short-range order
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity
81.30.Kf Martensitic transformations

Mechanical properties, glass transition temperature, and bond enthalpy trends of high metalloid Fe-based bulk metallic glasses

X. J. Gu, S. Joseph Poon, Gary J. Shiflet, and Michael Widom

Appl. Phys. Lett. 92, 161910 (2008); http://dx.doi.org/10.1063/1.2917577 (3 pages) | Cited 15 times

Online Publication Date: 25 April 2008

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Mechanical properties and glass transition temperatures (Tg) of Fe–Cr–Mo–P–C–B bulk metallic glasses containing up to 27 at. % metalloids have been studied. The shear modulus (G) is found to decrease with increasing metalloid content and a maximum plastic strain of ∼ 3% is obtained, despite the increase in the number of strong metal-metalloid bonds. Also, Tg increases with the decrease in G, in contrast to usual behavior. By employing first-principles calculations, the results are discussed in light of atomic bonding and connectivity in the amorphous network. The findings are relevant to understanding ductility and glass transition of metallic glasses.
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64.70.pe Metallic glasses
62.20.de Elastic moduli
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.fk Ductility, malleability
81.05.Kf Glasses (including metallic glasses)

Single-crystal epitaxial thin films of SrFeO2 with FeO2 “infinite layers”

Satoru Inoue, Masanori Kawai, Yuichi Shimakawa, Masaichiro Mizumaki, Naomi Kawamura, Takashi Watanabe, Yoshihiro Tsujimoto, Hiroshi Kageyama, and Kazuyoshi Yoshimura

Appl. Phys. Lett. 92, 161911 (2008); http://dx.doi.org/10.1063/1.2913164 (3 pages) | Cited 19 times

Online Publication Date: 25 April 2008

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Single-crystal thin films of SrFeO2, which is an oxygen-deficient perovskite with “infinite layers” of Fe2+O2, were prepared by using CaH2 for low-temperature reduction of epitaxial SrFeO2.5 single-crystal films deposited on KTaO3 substrates. This reduction process, removing oxygen ions from the perovskite structure framework and causing rearrangements of oxygen ions, topotactically transforms the brownmillerite SrFeO2.5 to the c-axis oriented SrFeO2.
Show PACS
81.15.Fg Pulsed laser ablation deposition
82.30.-b Specific chemical reactions; reaction mechanisms
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
61.66.Fn Inorganic compounds
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