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26 Mar 2007

Volume 90, Issue 13, Articles (13xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 90, 134101 (2007); http://dx.doi.org/10.1063/1.2679209 (3 pages)

S. Srinivasan, J. Hiller, B. Kabius, and O. Auciello
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Erasing diffraction orders: Opal versus Langmuir-Blodgett colloidal crystals

S. G. Romanov, M. Bardosova, D. E. Whitehead, I. M. Povey, M. Pemble, and C. M. Sotomayor Torres

Appl. Phys. Lett. 90, 133101 (2007); http://dx.doi.org/10.1063/1.2714198 (3 pages) | Cited 18 times

Online Publication Date: 26 March 2007

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The optical transmission of photonic crystals self-assembled from colloidal nanospheres in opals and assembled from two-dimensional colloidal crystals in a periodic stack by the Langmuir-Blodgett technique has been compared. Elimination of all related zero order diffraction resonances other than that from growth planes and broadening and deepening of the remaining one-dimensional diffraction resonance have been observed for samples prepared by the Langmuir-Blodgett approach, which are explained in terms of the partial disorder of a crystal lattice.
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78.67.-n Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
42.70.Qs Photonic bandgap materials
82.70.Dd Colloids

Capturing and depositing one nanoobject at a time: Single particle dip-pen nanolithography

Ying Wang, Yi Zhang, Bin Li, Junhong Lü, and Jun Hu

Appl. Phys. Lett. 90, 133102 (2007); http://dx.doi.org/10.1063/1.2714287 (2 pages) | Cited 11 times

Online Publication Date: 26 March 2007

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A convenient technique for transferring nanoparticles in a one-particle-at-a-time fashion is presented. This technique, termed as single particle dip-pen nanolithography, employs an atomic force microscope (AFM) tip to “grab” individual gold nanoparticles on surfaces. The nanoparticles attached to the AFM tips can be then controllably released and redeposited site specifically on surfaces. Patterns composed of single gold particles have been fabricated.
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81.16.Nd Micro- and nanolithography
81.16.Rf Micro- and nanoscale pattern formation

Coaxial nanocable: Carbon nanotube core sheathed with boron nitride nanotube

Zhuhua Zhang, Wanlin Guo, and Guo’an Tai

Appl. Phys. Lett. 90, 133103 (2007); http://dx.doi.org/10.1063/1.2714997 (3 pages) | Cited 9 times

Online Publication Date: 26 March 2007

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A coaxial nanocable model consisting of conductive carbon nanotube core and boron nitride nanotube sheath is proposed by ab initio calculations. The conduction electron density is mainly concentrated on the inner carbon shell at the optimal interwall distance about 0.35 nm. The conductivity of the core carbon nanotube and the insulation of the boron nitride nanotube sheath are found to be rather tolerant to mechanical deformation.
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73.22.-f Electronic structure of nanoscale materials and related systems
73.63.-b Electronic transport in nanoscale materials and structures
71.15.-m Methods of electronic structure calculations
62.25.-g Mechanical properties of nanoscale systems
81.40.Lm Deformation, plasticity, and creep
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Experimental observation of a band gap in individual Mn12 molecules on Au(111)

S. Voss, M. Fonin, U. Rüdiger, M. Burgert, and U. Groth

Appl. Phys. Lett. 90, 133104 (2007); http://dx.doi.org/10.1063/1.2716867 (3 pages) | Cited 18 times

Online Publication Date: 26 March 2007

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The authors report on the electronic properties of individual molecules of two Mn12 derivatives chemically grafted on the functionalized Au(111) surface studied by means of ultrahigh vacuum scanning tunneling microscopy/spectroscopy at room temperature. Reproducible current-voltage curves were obtained from both Mn12 molecules, showing a well defined wide band gap. In agreement with the tunneling spectroscopy results, the bias voltage variation upon scanning leads to apparent height changes of the Mn12 clusters. The authors discuss these findings in the light of the recent band structure calculations and electronic transport measurements on single Mn12 molecules.
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73.22.-f Electronic structure of nanoscale materials and related systems
71.20.Eh Rare earth metals and alloys

Flow behavior of an Eyring fluid in a nanotube: The effect of the slip boundary condition

Fuqian Yang

Appl. Phys. Lett. 90, 133105 (2007); http://dx.doi.org/10.1063/1.2717019 (3 pages) | Cited 6 times

Online Publication Date: 26 March 2007

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The flow of an Eyring fluid in a nanotube is analyzed by using continuum mechanics. The results reveal that the Eyring fluid flows like a Newtonian fluid at small pressure gradient and a pluglike fluid at high pressure gradient. The flow rate of the Eyring fluid in the nanotube at high pressure gradient with the Navier slip condition is several orders of magnitude higher than the Hagen-Poiseuille result for the flow of Newtonian fluids in the nanotube. This trend is similar to the experimental results reported in literature, suggesting that the Eyring fluid can be used to model nanoscale fluid flow.
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47.50.Cd Modeling
47.61.Fg Flows in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS)
47.60.-i Flow phenomena in quasi-one-dimensional systems
47.45.Gx Slip flows and accommodation
47.85.Np Fluidics

Investigation of multilayer local tilt within long portion of single Co/Cu nanowires

D. Pullini, G. Innocenti, D. Busquets, and A. Ruotolo

Appl. Phys. Lett. 90, 133106 (2007); http://dx.doi.org/10.1063/1.2715121 (3 pages) | Cited 3 times

Online Publication Date: 26 March 2007

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In this work arrays of Co/Cu multilayer nanowires were fabricated by electrodeposition to develop giant magnetoresistive sensors. Structure and morphology defects within 6 μm long portions of single nanowires have been probed by electron and ion-beam microscopies. It has been discovered that the most recurrent growth defect is a tilt of the nanowire layers, which varies along the length of the nanowires, this effect being more significant for nanowires of larger diameters; nevertheless, the nanowire arrays fabricated in this work demonstrated a magnetoresistive response which is very close to the behavior of analogous systems previously reported in the literature.
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68.65.Ac Multilayers
81.15.Pq Electrodeposition, electroplating
75.47.De Giant magnetoresistance
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

Ferroelectric domains and piezoelectricity in monocrystalline Pb(Zr,Ti)O3 nanowires

J. Wang, C. S. Sandu, E. Colla, Y. Wang, W. Ma, R. Gysel, H. J. Trodahl, N. Setter, and M. Kuball

Appl. Phys. Lett. 90, 133107 (2007); http://dx.doi.org/10.1063/1.2716842 (3 pages) | Cited 25 times

Online Publication Date: 27 March 2007

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Monocrystalline lead zirconate titanate nanowires were grown by a polymer assisted solvothermal technique. X-ray and electron diffractions confirmed tetragonal perovskite structure and a [001] orientation along the wire axis, respectively. Raman scattering was used to analyze the structure and composition of single wires. Ferroelectric/ferroelastic domain walls were imaged by transmission electron microscopy, showing some domains with polarization directions along the wire axis and some perpendicular to it. The domain walls disappeared upon heating above the ferroelectric phase transition at 460 °C. Ferroelectric switching, as well as piezoelectric activity and hysteresis, were shown locally using piezoelectric force microscopy.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.Dj Domain structure; hysteresis
77.65.-j Piezoelectricity and electromechanical effects
78.30.Hv Other nonmetallic inorganics
77.80.B- Phase transitions and Curie point
77.80.Fm Switching phenomena

Laser direct writing carbon nanotube arrays on transparent substrates

Zhuo Chen, Yang Wei, Chunxiang Luo, Kaili Jiang, Lina Zhang, Qunqing Li, Shoushan Fan, and Jiancun Gao

Appl. Phys. Lett. 90, 133108 (2007); http://dx.doi.org/10.1063/1.2717530 (3 pages) | Cited 9 times

Online Publication Date: 27 March 2007

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The authors report the synthesis of multiwalled carbon nanotubes on transparent substrates by utilizing a diode laser to locally heat the catalysts to high temperature. Well-aligned bamboo-shaped multiwalled carbon nanotubes can be synthesized on glass substrate covered with a carbon black layer. If the carbon black was substituted by the commercial graphite inner coating, randomly oriented but high quality multiwalled carbon nanotubes were obtained with excellent field emission performance. This approach facilitates the fabrication of multiwalled carbon nanotube field emitters for field emission flat panel displays without limitations on the geometry size and temperature requirement of the substrate.
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81.07.De Nanotubes
61.46.Fg Nanotubes
42.62.-b Laser applications
85.45.Db Field emitters and arrays, cold electron emitters
85.35.Kt Nanotube devices

Self-breaking in planar few-atom Au constrictions for nanometer-spaced electrodes

K. O’Neill, E. A. Osorio, and H. S. J. van der Zant

Appl. Phys. Lett. 90, 133109 (2007); http://dx.doi.org/10.1063/1.2716989 (3 pages) | Cited 29 times

Online Publication Date: 28 March 2007

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The authors present results on electromigrated Au nanojunctions broken near the conductance quantum of 77.5 μS. At room temperature it is found that wires, initially narrowed by an actively-controlled electromigration technique down to a few conductance quanta, continue to narrow after removing the applied voltage. Separate electrodes form as mobile gold atoms continuously reconfigure the constriction. They find, from results obtained on over 300 samples, no evidence for gold cluster formation in junctions broken without an applied voltage, implying that gold clusters may be avoided by using this self-breaking technique.
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66.30.Qa Electromigration
61.46.Bc Structure of clusters (e.g., metcars; not fragments of crystals; free or loosely aggregated or loosely attached to a substrate)

Local force gradients on Si(111) during simultaneous scanning tunneling/atomic force microscopy

H. Özgür Özer, Simon J. O’Brien, and John B. Pethica

Appl. Phys. Lett. 90, 133110 (2007); http://dx.doi.org/10.1063/1.2717115 (3 pages) | Cited 12 times

Online Publication Date: 28 March 2007

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The authors report simultaneous scanning tunneling and force imaging of Si(111) 7×7 with sub-angstrom oscillation amplitudes. Both constant height and constant current scans with tungsten tips/levers always showed larger attractive stiffness over corner holes than over adatoms, the opposite of theoretical expectations. Constant height scans show that this cannot be explained by interaction of tip motion with long range forces. Silicon levers, however, sometimes exhibited inversions of force contrast following local tip changes. The authors suggest that there may be charge variations between atomic sites on the surface, which produce electrostatic tip forces additional to the covalent forces usually regarded as dominant.
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68.47.Fg Semiconductor surfaces
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)

Epitaxial growth of manganese silicide nanowires on Si(111)-7×7 surfaces

Z.-Q. Zou, H. Wang, D. Wang, Q.-K. Wang, J.-J. Mao, and X.-Y. Kong

Appl. Phys. Lett. 90, 133111 (2007); http://dx.doi.org/10.1063/1.2717580 (3 pages) | Cited 14 times

Online Publication Date: 28 March 2007

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Reactive epitaxial growth of manganese silicide on a Si(111)-7×7 surface at low coverage is studied using scanning tunneling microscopy. Besides tabular and three-dimensional islands observed previously on the Mn/Si system, Mn silicide is found to form nanowires (NWs) on the Si(111)-7×7 surface at temperatures above ∼ 500 °C. The NWs oriented along [10math], [01math], and [1math0], three equivalent directions, with equal probability. Well-ordered atomic arrangement observed on an ultrafine NW indicates that the NWs are crystalline. Scanning tunneling spectroscopy measurements show that the NWs exhibit a semiconducting character with a band gap of ∼ 0.8 eV, which is consistent with that of bulk MnSi1.7.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
81.05.Hd Other semiconductors
81.16.-c Methods of micro- and nanofabrication and processing
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Auger recombination and intraband absorption of two-photon-excited carriers in colloidal CdSe quantum dots

Yingli Qu, Wei Ji, Yuangang Zheng, and Jackie Y. Ying

Appl. Phys. Lett. 90, 133112 (2007); http://dx.doi.org/10.1063/1.2716067 (3 pages) | Cited 12 times

Online Publication Date: 29 March 2007

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Auger recombination, quantized Auger rate, and intraband absorption of two-photon-excited carriers in colloidal CdSe quantum dots have been investigated systematically with femtosecond Z scans and transient absorption measurements. The Auger constant is revealed to be on the order of 10−30 cm6 s−1, while the intraband absorption cross sections are found to be in the range of 10−18–10−17 cm2. The authors’ experimental evidence demonstrates that the Auger recombination or the intraband absorption takes place under the condition that the average electron-hole pair per quantum dot is in excess of the unity.
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78.67.Hc Quantum dots
42.65.-k Nonlinear optics
73.63.Kv Quantum dots
78.47.-p Spectroscopy of solid state dynamics
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Three-photon absorption in ZnSe and ZnSe/ZnS quantum dots

Amit D. Lad, P. Prem Kiran, G. Ravindra Kumar, and Shailaja Mahamuni

Appl. Phys. Lett. 90, 133113 (2007); http://dx.doi.org/10.1063/1.2714994 (3 pages) | Cited 20 times

Online Publication Date: 29 March 2007

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ZnSe and ZnSe/ZnS core/shell quantum dots (QDs) of two different sizes (4.5 and 3.5 nm) have been synthesized. The nonlinear absorption is measured at 1064 nm using a 35 ps laser with an open aperture Z-scan setup. Three-photon absorption (3PA) has been observed in ZnSe and ZnSe/ZnS QDs. 3PA cross section is found to be about four orders of magnitude larger than bulk ZnSe, and three orders of magnitude higher than ZnS QDs. 3PA cross section is found to be increased in ZnSe and in ZnSe/ZnS QDs with decreasing size from 4.5 to 3.5 nm, due to strong confinement effect.
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78.67.Hc Quantum dots
42.65.-k Nonlinear optics
78.47.-p Spectroscopy of solid state dynamics
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Large-area two-dimensional photonic crystals of metallic nanocylinders based on colloidal gold nanoparticles

Xinping Zhang, Baoquan Sun, Hongcang Guo, Nicolas Tetreault, Harald Giessen, and Richard H. Friend

Appl. Phys. Lett. 90, 133114 (2007); http://dx.doi.org/10.1063/1.2717567 (3 pages) | Cited 14 times

Online Publication Date: 29 March 2007

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We report on the fabrication of two-dimensional periodic arrays of gold nanocylinders with an aspect ratio larger than 2 using solution-processible gold nanoparticles. We utilize the large surface energy of the melted gold in an annealing process at 260 °C to confine the gold nanoparticles into the nanoholes consisting the mask, on which the colloidal gold nanoparticles are spin coated, producing a two-dimensional square lattice of gold nanocylinders. The height of the nanocylinders is larger than 200 nm above an indium-tin-oxide waveguide layer and their diameter is about 100 nm. Optical extinction spectrum measurements show excellent particle plasmon resonances of the nanocylinders.
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81.16.-c Methods of micro- and nanofabrication and processing
61.46.-w Structure of nanoscale materials
42.70.Qs Photonic bandgap materials
68.35.Md Surface thermodynamics, surface energies
81.40.Gh Other heat and thermomechanical treatments
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons

Magnetic alignment of ZnO nanowires for optoelectronic device applications

Sang-Won Lee, Min-Chang Jeong, Jae-Min Myoung, Gee-Sung Chae, and In-Jae Chung

Appl. Phys. Lett. 90, 133115 (2007); http://dx.doi.org/10.1063/1.2717575 (3 pages) | Cited 19 times

Online Publication Date: 29 March 2007

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Ni caps on ZnO nanowires were synthesized to control the direction and position of these nanowires using magnetism. Vertically ordered ZnO nanowires were grown 15 μm in length by metal organic chemical vapor deposition and then ferromagnetic Ni was capped on top of the nanowires by sputtering. The synthesized nanowires were aligned at the edge of the magnetized Ni patterns by applying a magnetic field. The density of the aligned nanowires depended on the magnetic force of the Ni patterns. Nanowire-based ultraviolet sensors were demonstrated using the magnetic alignment method.
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75.50.Pp Magnetic semiconductors
75.50.Cc Other ferromagnetic metals and alloys
75.50.Tt Fine-particle systems; nanocrystalline materials
85.60.Gz Photodetectors (including infrared and CCD detectors)
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Encapsulation of segmented Pd–Co nanocomposites into vertically aligned carbon nanotubes by plasma-hydrogen-induced demixing

Takeshi Fujita, Yasuhiko Hayashi, Tomoharu Tokunaga, T. Butler, N. L. Rupesinghe, K. B. K. Teo, and G. A. J. Amaratunga

Appl. Phys. Lett. 90, 133116 (2007); http://dx.doi.org/10.1063/1.2718268 (3 pages) | Cited 6 times

Online Publication Date: 29 March 2007

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Vertically aligned carbon nanotubes (VA-CNTs) filled with Pd–Co nanocomposites on an Si substrate have been synthesized by microwave plasma-enhanced chemical vapor deposition. It was confirmed that adjacent Pd–Co nanocomposites in the VA-CNTs were compositionally separated. Most CNTs contained Co pillars on top; however, Pd pillars were rarely present. The strong magnetic induction from an individual Co pillar was revealed by electron holography. The simultaneous phenomenon of the demixing by plasma hydrogen irradiation and the preferential encapsulation into CNTs realized the unique Pd–Co nanocomposites.
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81.07.De Nanotubes
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.77.Dq Plasma-based ion implantation and deposition
61.46.Fg Nanotubes

Dispersion of magnetic metals on expanded graphite for the shielding of electromagnetic radiations

Yuan Huang, Zheng Xu, Jianyi Shen, Tao Tang, and Runsheng Huang

Appl. Phys. Lett. 90, 133117 (2007); http://dx.doi.org/10.1063/1.2718269 (3 pages) | Cited 4 times

Online Publication Date: 29 March 2007

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The composites of nanoparticles of magnetic metals Co, Ni, and Ni–Fe dispersed on the nanolayers of expanded graphite (EG) were prepared by the impregnation of EG with ethanol solutions of metal acetates, followed by drying and reduction in H2. Such composites combined the properties of high electric conductivity of EG and magnetic conductivities of dispersed metals, and thus exhibited the high shielding effectiveness in a wide range of frequencies. Specifically, the composite containing 30%Ni and 70%EG reached the shielding effectiveness of 70–105 dB at frequencies from 300 kHz to 1.5 GHz.
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81.05.-t Specific materials: fabrication, treatment, testing, and analysis
81.07.-b Nanoscale materials and structures: fabrication and characterization
72.80.Tm Composite materials
75.47.Pq Other materials
07.50.Hp Electrical noise and shielding equipment

Effect of grain size and pores on the dielectric constant of nanocrystalline diamond films

Z. L. Wang, J. J. Li, Z. H. Sun, Y. L. Li, Q. Luo, C. Z. Gu, and Z. Cui

Appl. Phys. Lett. 90, 133118 (2007); http://dx.doi.org/10.1063/1.2718484 (3 pages) | Cited 9 times

Online Publication Date: 30 March 2007

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The nanocrystalline diamond films with different morphologies and roughness were synthesized by a bias-assisted hot filament chemical vapor deposition method. It was found that the nanocrystalline diamond film exhibited low-k dielectric properties with the increase of CH4 concentration during diamond deposition. The low-k nanocrystalline diamond film with grain size of around 40 nm and dielectric constant of 2.4 was obtained at the CH4 concentration of 16% and the bias of −140 V. The low dielectric constant can be mainly attributed to the decrease of diamond grain sizes and the formation of more nanopores in as-grown nanocrystalline diamond film, both of which were discussed in details based on the grain size determined band gap expansion effect and the two-phase dielectric mixing model, respectively.
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77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
73.20.At Surface states, band structure, electron density of states
68.55.-a Thin film structure and morphology
68.55.A- Nucleation and growth
61.43.Gt Powders, porous materials

Mechanics of precisely controlled thin film buckling on elastomeric substrate

Hanqing Jiang, Yugang Sun, John A. Rogers, and Yonggang Huang

Appl. Phys. Lett. 90, 133119 (2007); http://dx.doi.org/10.1063/1.2719027 (3 pages) | Cited 34 times

Online Publication Date: 30 March 2007

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Stretchable electronics has many important and emerging applications. Sun et al. [Nature Nanotech. 1, 201 (2006)] recently demonstrated stretchable electronics based on precisely controlled buckle geometries in GaAs and Si nanoribbons on elastomeric substrates. A nonlinear buckling model is presented in this letter to study the mechanics of this type of thin film/substrate system. An analytical solution is obtained for the buckling geometry (wavelength and amplitude) and the maximum strain in buckled thin film. This solution agrees very well with the experiments, and shows explicitly how buckling can significantly reduce the thin film strain to achieve the system stretchability.
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68.60.Bs Mechanical and acoustical properties
62.25.-g Mechanical properties of nanoscale systems
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity

Pulsed ion-beam induced nucleation and growth of Ge nanocrystals on SiO2

N. P. Stepina, A. V. Dvurechenskii, V. A. Armbrister, V. G. Kesler, P. L. Novikov, A. K. Gutakovskii, V. V. Kirienko, Zh. V. Smagina, and R. Groetzschel

Appl. Phys. Lett. 90, 133120 (2007); http://dx.doi.org/10.1063/1.2719163 (3 pages) | Cited 7 times

Online Publication Date: 30 March 2007

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Pulsed low-energy (200 eV) ion-beam induced nucleation during Ge deposition on thin SiO2 film was used to form dense homogeneous arrays of Ge nanocrystals. The ion-beam action is shown to stimulate the nucleation of Ge nanocrystals when being applied after thin Ge layer deposition. Temperature and flux variation was used to optimize the nanocrystal size and array density required for memory device. Kinetic Monte Carlo simulation shows that ion impacts open an additional channel of atom displacement from a nanocrystal onto SiO2 surface. This results both in a decrease in the average nanocrystal size and in an increase in nanocrystal density.
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81.07.Bc Nanocrystalline materials
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Cy Elemental semiconductors

Bias-induced local heating in atom-sized metal contacts at 77 K

Makusu Tsutsui, Shu Kurokawa, and Akira Sakai

Appl. Phys. Lett. 90, 133121 (2007); http://dx.doi.org/10.1063/1.2719682 (3 pages) | Cited 9 times

Online Publication Date: 30 March 2007

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Local heating in Zn atom-sized contacts is studied at 77 K under high biases. Switching rate ν of two-level fluctuations of the contact conductance is measured and statistically analyzed to estimate the contact effective temperature. Typical log ν increases linearly with the bias up to 0.35 V, which suggests negligible contact heating in the low-bias regime. Above 0.4 V, however, log ν rises steeply with the bias due to an onset of contact overheating. The estimated contact temperature rises more rapidly with the bias than the math dependence derived theoretically.
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81.05.Bx Metals, semimetals, and alloys
81.40.Gh Other heat and thermomechanical treatments
73.40.-c Electronic transport in interface structures

Free vibration analysis of fluid-conveying single-walled carbon nanotubes

C. D. Reddy, C. Lu, S. Rajendran, and K. M. Liew

Appl. Phys. Lett. 90, 133122 (2007); http://dx.doi.org/10.1063/1.2717554 (3 pages) | Cited 28 times

Online Publication Date: 30 March 2007

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The effect of fluid flow on the free vibration and instability of fluid-conveying single-walled carbon nanotubes is studied. The possibility of developing a technique to measure the mass flow rate of fluid is examined. Atomistic simulations and the continuum beam model are used. Simulations are performed to quantify the inertial, stiffness, Coriolis, and centrifugal forces generated by flow during the free vibration. A numerical expression is developed to measure the mass flow rate of the fluid velocities up to 40% of the critical flow velocity. This observation is useful to quantify the mass flow measurement of fluid conveying single-walled carbon nanotubes.
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47.80.Cb Velocity measurements
47.11.-j Computational methods in fluid dynamics
47.60.-i Flow phenomena in quasi-one-dimensional systems
47.61.Fg Flows in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS)
47.85.Np Fluidics
47.20.-k Flow instabilities

Coercivity and nanostructure in magnetic spinel Mg(Mn,Fe)2O4

C. L. Zhang, S. Yeo, Y. Horibe, Y. J. Choi, S. Guha, M. Croft, S.-W. Cheong, and S. Mori

Appl. Phys. Lett. 90, 133123 (2007); http://dx.doi.org/10.1063/1.2717568 (3 pages) | Cited 14 times

Online Publication Date: 30 March 2007

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When Fe ions in the ferrimagnetic cubic MgFe2O4 are replaced by Jahn-Teller (JT)-active Mn ions, the structure evolves with two-step processes. For example, the quenched cubic MgMn1.5Fe0.5O4 becomes tetragonal and JT distorted with slow cooling. However, with further slow cooling, the clustering tendency of JT-distorted Mn ions induces the formation of a checkerboard nano-self-assembly consisting of Mn-rich (tetragonal, paramagnetic) and -poor (cubic, ferrimagnetic) rods. This morphological evolution accompanies a drastic modification of ferrimagnetic properties, e.g., the magnetic coercivity changes by ∼ 25. The nanocheckerboard assembly with ferrimagnetic nanorods with large shape anisotropy can be a platform for ultra high-density memory devices.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Tt Fine-particle systems; nanocrystalline materials
75.30.Gw Magnetic anisotropy
75.50.Gg Ferrimagnetics
75.20.Ck Nonmetals
61.46.-w Structure of nanoscale materials
81.16.Dn Self-assembly

Coupling interaction in 1-3-type multiferroic composite thin films

XiaoYan Lu, Biao Wang, Yue Zheng, and Earle Ryba

Appl. Phys. Lett. 90, 133124 (2007); http://dx.doi.org/10.1063/1.2717585 (3 pages) | Cited 16 times

Online Publication Date: 30 March 2007

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Using the time-dependent Ginzburg-Landau equation, the coupling interaction of the ferroelectric (FE) and ferromagnetic (FM) phases in epitaxial 1-3-type multiferroic thin films was investigated considering the effect of elastic stress arising from the FE/FM and film/substrate interfaces. The result of the authors shows that the maximum polarization and magnetization appear with the FM fractions of 70% and 30%, respectively. The significant changes of the FE and FM properties are caused by the special structure in which the induced misfit strain greatly affects the anisotropy of the crystals and the properties of the materials.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.80.+q Magnetomechanical effects, magnetostriction
77.80.-e Ferroelectricity and antiferroelectricity
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.F- Deformation and plasticity
75.30.Gw Magnetic anisotropy
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