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

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

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

10 Sep 2012

Volume 101, Issue 11, Articles (11xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 101, 113302 (2012); http://dx.doi.org/10.1063/1.4749791 (4 pages)

Chang-Hoon Shim, Shuzo Hirata, Juro Oshima, Tomohiko Edura, Reiji Hattori, and Chihaya Adachi
Enlarge Image | Read More
Page 2 of 5 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Blue shift induced by extrinsic spin-orbit coupling on monolayer graphene

A. Phirouznia, S. Safari Shateri, J. Poursamad Bonab, and K. Jamshidi-Ghaleh

Appl. Phys. Lett. 101, 111905 (2012); http://dx.doi.org/10.1063/1.4752101 (4 pages)

Online Publication Date: 12 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of substrate induced spin-orbit (SO) interaction on the transverse dielectric function of a single plane of graphene has been investigated. The Lindhard model approach was then employed to obtain the transverse dielectric function. The dependence of dielectric function on the SO coupling of the graphene sheet with the substrate was theoretically studied. Numerical results show that increasing the Rashba coupling strength results in a blue shift of the van Hove singularities in the linear dielectric response function. Controllable blue shift opens up ways for a variety of device applications.
Show PACS
78.67.Wj Optical properties of graphene
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Temperature dependence of chemical-vapor deposition of pure boron layers from diborane

V. Mohammadi, W. B. de Boer, and L. K. Nanver

Appl. Phys. Lett. 101, 111906 (2012); http://dx.doi.org/10.1063/1.4752109 (4 pages) | Cited 2 times

Online Publication Date: 12 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Surface reaction mechanisms are investigated to determine the activation energies of pure boron (PureB) layer deposition at temperatures from 350 °C to 850 °C when using chemical-vapor deposition from diborane in a commercial Si/SiGe epitaxial reactor with either hydrogen or nitrogen as carrier gas. Three distinguishable regions are identified to be related to the dominance of specific chemical reaction mechanisms. Activation energies in H2 are found to be 28 kcal/mol below 400 °C and 6.5 kcal/mol from 400 °C to 700 °C. In N2, the value decreases to 2.1 kcal/mol for all temperatures below 700 °C. The rate of hydrogen desorption is decisive for this behavior.
Show PACS
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.43.Nr Desorption kinetics
68.43.Mn Adsorption kinetics

Charge dynamics and electronic structures of monolayer graphene with molecular doping

C. C. Shen, C. T. Lin, L. J. Li, and H. L. Liu

Appl. Phys. Lett. 101, 111907 (2012); http://dx.doi.org/10.1063/1.4752131 (4 pages)

Online Publication Date: 13 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
THz absorption and spectroscopic ellipsometry were used to investigate the charge dynamics and electronic structures of monolayer graphene with doping by triazine. The absorption spectrum of the triazine-doped film shows an optical excitation near 5.1 eV that is blue shifted compared with that of undoped analog. THz conductivity displays a coherent response of itinerant charge carriers at zero frequency and a disorder-induced finite frequency peak around 155 cm−1. Drude plasma frequency (∼4400 cm−1) decreases with decreasing temperature while carrier relaxation time (∼13 fs) is almost temperature independent, implying the semiconducting behavior with thermal activation energy of 3 meV.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.70.Gq Microwave and radio-frequency interactions
71.20.Mq Elemental semiconductors
73.61.Cw Elemental semiconductors
73.22.Pr Electronic structure of graphene
73.61.Wp Fullerenes and related materials

Self-sustaining oxidation initiated by rapid formation reactions in multilayer foils

H. Joress, S. C. Barron, K. J. T. Livi, N. Aronhime, and T. P. Weihs

Appl. Phys. Lett. 101, 111908 (2012); http://dx.doi.org/10.1063/1.4752133 (4 pages)

Online Publication Date: 13 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Here we report that a self-sustaining oxidation of a multilayer foil can be ignited by an intermetallic formation reaction, releasing ∼4× the energy of the formation reaction. We examine foils with overall chemistries of 3Al:2Ni, 3Al:Zr, and Al:Zr and find that only the latter experiences significant oxidation. The Al:Zr samples initially react to form intermetallics and reach ∼1500 K in <10 ms. The samples then oxidize in air, absorbing ∼30 at. % O and remaining at ∼1400 K for >2.0 s. The phases within the Al:Zr foils are characterized and temperature-time profiles are examined to predict the heat generated by the oxidation reaction.
Show PACS
82.30.-b Specific chemical reactions; reaction mechanisms
82.60.Cx Enthalpies of combustion, reaction, and formation
68.65.Ac Multilayers
82.33.Vx Reactions in flames, combustion, and explosions

Electronic structure and optical properties of β-FeSi2(100)/Si(001) interface at high pressure

L. Z. Liu, X. L. Wu, X. X. Liu, J. C. Shen, T. H. Li, and Paul K. Chu

Appl. Phys. Lett. 101, 111909 (2012); http://dx.doi.org/10.1063/1.4752154 (4 pages)

Online Publication Date: 13 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electronic structure and optical absorption properties of the β-FeSi2(100)/Si(001) interface are investigated by first-principle calculation at high pressure. As the pressure increases, the optical gap decreases sharply, reaches a minimum, and then increases slowly. Structural analysis reveals that the Si(001) slab partially offsets the pressure exerted on the β-FeSi2 (100) interface, thus downshifting the lowest unoccupied electronic states of the interface and decreasing the optical gap. As the pressure increases further, this offsetting effect weakens and the optical gap increases again gradually. Hence, a high pressure plays an important role in the optical behavior.
Show PACS
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.20.Ps Other inorganic compounds
61.66.Fn Inorganic compounds
71.15.-m Methods of electronic structure calculations
62.50.-p High-pressure effects in solids and liquids

Effect of Pd on the Ni2Si stress relaxation during the Ni-silicide formation at low temperature

M. Putero and D. Mangelinck

Appl. Phys. Lett. 101, 111910 (2012); http://dx.doi.org/10.1063/1.4752716 (5 pages)

Online Publication Date: 14 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The thermally induced solid-state reaction between a 50-nm-thick Ni(6%Pd) layer and a Si(100) substrate was investigated using in situ and simultaneous x-ray diffraction and sheet resistance. The reaction begins with the growth of the stressed δ-Ni2Si phase, and the transient θ-Ni2Si. At the end of the θ-Ni2Si consumption, a NiSi seed is formed. Then, the δ-Ni2Si relaxation occurs simultaneously with its subsequent growth and the Pd out diffusion from the unreacted Ni(Pd) layer. It is suggested that the driving force for the Pd diffusion out of the metal layer is linked to both the higher solubility of Pd in NiSi compared to Ni2Si and to the Ni2Si relaxation.
Show PACS
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
68.60.Bs Mechanical and acoustical properties
64.75.Bc Solubility
81.15.Cd Deposition by sputtering
68.55.aj Insulators

Electron backscatter diffraction on femtosecond laser sulfur hyperdoped silicon

Thomas Gimpel, Ingmar Höger, Fritz Falk, Wolfgang Schade, and Stefan Kontermann

Appl. Phys. Lett. 101, 111911 (2012); http://dx.doi.org/10.1063/1.4752454 (3 pages)

Online Publication Date: 14 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper analyzes the impact of femtosecond laser pulse irradiation on the crystallinity of silicon wafers by means of electron backscatter diffraction (EBSD) measurements. EBSD based image quality maps and orientation imaging microscopy maps are correlated to the grade of the silicon crystallinity. We analyze the impact of accumulated net laser irradiation originating from a laser spot overlap that is necessary to process macroscopic areas, e.g., for sulfur doping of semiconductor devices. Furthermore, we demonstrate that post processing annealing recovers crystallinity and therefore allows fs-laser processed silicon to be used in semiconductor device manufacturing.
Show PACS
81.16.-c Methods of micro- and nanofabrication and processing
42.62.-b Laser applications
81.05.Cy Elemental semiconductors
79.20.Kz Other electron-impact emission phenomena
78.47.J- Ultrafast spectroscopy (<1 psec)
61.72.Cc Kinetics of defect formation and annealing

Convergent beam electron-diffraction investigation of lattice mismatch and static disorder in GaAs/GaAs1−xNx intercalated GaAs/GaAs1−xNx:H heterostructures

S. Frabboni, V. Grillo, G. C. Gazzadi, R. Balboni, R. Trotta, A. Polimeni, M. Capizzi, F. Martelli, S. Rubini, G. Guzzinati, and F. Glas

Appl. Phys. Lett. 101, 111912 (2012); http://dx.doi.org/10.1063/1.4752464 (4 pages)

Online Publication Date: 14 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Hydrogen incorporation in diluted nitride semiconductors dramatically modifies the electronic and structural properties of the crystal through the creation of nitrogen-hydrogen complexes. We report a convergent beam electron-diffraction characterization of diluted nitride semiconductor-heterostructures patterned at a sub-micron scale and selectively exposed to hydrogen. We present a method to determine separately perpendicular mismatch and static disorder in pristine and hydrogenated heterostructures. The roles of chemical composition and strain on static disorder have been separately assessed.
Show PACS
61.66.Fn Inorganic compounds
61.72.J- Point defects and defect clusters
back to top
RSS Feeds

P-type ZnO thin films achieved by N+ ion implantation through dynamic annealing process

M. A. Myers, M. T. Myers, M. J. General, J. H. Lee, L. Shao, and H. Wang

Appl. Phys. Lett. 101, 112101 (2012); http://dx.doi.org/10.1063/1.4751467 (5 pages) | Cited 1 time

Online Publication Date: 10 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
ZnO thin films were grown on sapphire (0001) substrates by pulsed-laser deposition at 700 °C. 70 keV N+ ion implantation was performed under various temperatures and fluences in the range of 300−460 °C and 3.0×1014−1.2×1015 cm−2, respectively. Hall measurements indicate that the ZnO films implanted at 460 °C are p-type for all fluences used herein. Hole-carrier concentrations lie in the range of 2.4×1016−5.2×1017 cm−3, hole mobilities in the range of 0.7−3.7 cm2 V−1 s−1, and resistivities between 18−71 Ωcm. Transmission-electron microscopy reveals major microstructural differences between the n-type and p-type films. Ion implantation at elevated temperatures is shown to be an effective method to introduce increased concentrations of p-type N dopants while reducing the amount of stable post-implantation disorder.
Show PACS
73.61.Ga II-VI semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
72.20.My Galvanomagnetic and other magnetotransport effects
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Fg Pulsed laser ablation deposition
81.40.Gh Other heat and thermomechanical treatments

Atomic structure of prismatic stacking faults in nonpolar a-plane GaN epitaxial layers

Yan-Ling Hu, Stephan Krämer, Paul T. Fini, and James S. Speck

Appl. Phys. Lett. 101, 112102 (2012); http://dx.doi.org/10.1063/1.4750238 (4 pages)

Online Publication Date: 10 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this study, a-plane GaN was grown on r-plane sapphire by sidewall lateral epitaxial overgrowth. Prismatic stacking faults (PSFs) in the window region of the GaN layer were identified to have an atomic configuration similar to the model presented by Northrup [Appl. Phys. Lett. 72, 2316 (1998)], which was demonstrated by comparing high-angle annular dark-field scanning transmission electron microscopy images with the atomic configurations of the Drum model, the Amelinckx model, and simplified Northrup model, respectively. The Northrup PSF structure has been further confirmed by the scattering contrast analysis in transmission electron microscopy experiments.
Show PACS
68.55.ag Semiconductors
61.72.Nn Stacking faults and other planar or extended defects
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.05.Ea III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Irradiation induced modification in transport properties of LaNiO3 thin films: An x-ray absorption study

Yogesh Kumar, Abhinav Pratap Singh, S. K. Sharma, R. J. Choudhary, P. Thakur, M. Knobel, N. B. Brookes, and Ravi Kumar

Appl. Phys. Lett. 101, 112103 (2012); http://dx.doi.org/10.1063/1.4752005 (4 pages)

Online Publication Date: 11 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Highly c-axis oriented LaNiO3 thin films are grown on LaAlO3 (001) single crystal substrates using rf-magnetron sputtering. Swift heavy ion irradiation induced variations in structural and electrical transport properties of deposited films are studied. Pristine film shows unusual insulating character while the irradiated film exhibits metallic behaviour. X-ray diffraction study indicates that irradiation improves the crystalline character of films while retaining the oriented single phase growth. Electronic structure measurements performed using x-ray absorption spectroscopy at O K, La M5,4, and Ni L3,2-edges reveal that Ni-O hybridization-controlled localization of charge carriers is responsible for the observed transport behaviour.
Show PACS
73.61.Ng Insulators
78.70.Dm X-ray absorption spectra
68.55.aj Insulators
61.80.Jh Ion radiation effects
81.15.Cd Deposition by sputtering

Comparative study of solution-processed carbon nanotube network transistors

Sung-Jin Choi, Chuan Wang, Cheuk Chi Lo, Patrick Bennett, Ali Javey, and Jeffrey Bokor

Appl. Phys. Lett. 101, 112104 (2012); http://dx.doi.org/10.1063/1.4752006 (4 pages) | Cited 2 times

Online Publication Date: 11 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Carbon nanotube networks in thin-film type transistors were studied experimentally, comparing the use of pre-separated semiconducting enriched nanotubes (90% and 99% purity) to examine how topology affects the properties of the devices. Measurements are reported for two deposition methods used for network formation: random and spin-aligned deposition methods. The results show that the thin-film transistors fabricated via spin-aligned deposition demonstrate better electrical uniformity and performance than those produced by the random network deposition method. Our results imply that coverage and alignment are strongly correlated with the properties of the devices and should therefore be simultaneously optimized for improved electrical uniformity and performance.
Show PACS
85.30.Tv Field effect devices
85.35.Kt Nanotube devices

Enhancing threshold voltage of AlGaN/GaN high electron mobility transistors by nano rod structure: From depletion mode to enhancement mode

Rong Xuan, Wei-Hong Kuo, Chih-Wei Hu, Suh-Fang Lin, and Jenn-Fang Chen

Appl. Phys. Lett. 101, 112105 (2012); http://dx.doi.org/10.1063/1.4752113 (3 pages)

Online Publication Date: 12 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper presents an approach in fabricating normally off AlGaN/GaN high electron mobility transistors (HEMTs). The fabrication technique was based on the carbon-doped GaN epitaxy layers on silicon substrate and the nano rod structure of the gate region in AlGaN/GaN HEMTs. Using this method, the threshold voltage of AlGaN/GaN HEMTs can be shifted from −2 V in a conventional depletion-mode (D-mode) AlGaN/GaN HEMT to 2 V in an enhancement-mode (E-mode) AlGaN/GaN HEMT.
Show PACS
85.30.Tv Field effect devices

Structural properties and band offset determination of p-channel mixed As/Sb type-II staggered gap tunnel field-effect transistor structure

Y. Zhu, N. Jain, D. K. Mohata, S. Datta, D. Lubyshev, J. M. Fastenau, A. K. Liu, and M. K. Hudait

Appl. Phys. Lett. 101, 112106 (2012); http://dx.doi.org/10.1063/1.4752115 (4 pages) | Cited 2 times

Online Publication Date: 12 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The structural properties and band offset determination of p-channel staggered gap In0.7Ga0.3As/GaAs0.35Sb0.65 heterostructure tunnel field-effect transistor (TFET) grown by molecular beam epitaxy (MBE) were investigated. High resolution x-ray diffraction revealed that the active layers are strained with respect to “virtual substrate.” Dynamic secondary ion mass spectrometry confirmed an abrupt junction profile at the In0.7Ga0.3As/GaAs0.35Sb0.65 heterointerface and minimal level of intermixing between As and Sb atoms. The valence band offset of 0.37 ± 0.05 eV was extracted from x-ray photoelectron spectroscopy. A staggered band lineup was confirmed at the heterointerface with an effective tunneling barrier height of 0.13 eV. Thus, MBE-grown staggered gap In0.7Ga0.3As/GaAs0.35Sb0.65 TFET structures are a promising p-channel option to provide critical guidance for the future design of mixed As/Sb type-II based complementary logic and low power devices.
Show PACS
85.30.Tv Field effect devices
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
71.20.Nr Semiconductor compounds
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Multiple implantation and multiple annealing of phosphorus doped germanium to achieve n-type activation near the theoretical limit

Jeehwan Kim, Stephen W. Bedell, and Devendra K. Sadana

Appl. Phys. Lett. 101, 112107 (2012); http://dx.doi.org/10.1063/1.4751845 (3 pages)

Online Publication Date: 14 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Full activation of n-type dopant in germanium (Ge) reaching to its solid solubility has never been achieved by using ion implantation doping technique. This is because implantation of dopants always leaves defects such as vacancy and interstitials in the Ge crystal. While implantation-induced defects are electrically neutral for the most of semiconductor materials, they are electrically positive for Ge resulting in compensation of n-type dopants. In this Letter, we verified that 5 × 1019 P/cm3 is the maximum active concentration, which can be fully activated in germanium “without leaving implantation damage” per implantation/annealing cycle. The repetition of implantation and annealing of phosphorous (P) with the concentration of 5 × 1019 cm−3 leads to the activation of 1 × 1020 P/cm3 close to its solid solubility limit of 2 × 1020 P/cm3.
Show PACS
61.72.uf Ge and Si
61.72.jd Vacancies
61.72.jj Interstitials
64.75.Bc Solubility

Degradation and passivation of CuInSe2

David Regesch, Levent Gütay, Jes K. Larsen, Valérie Deprédurand, Daisuke Tanaka, Yasuhiro Aida, and Susanne Siebentritt

Appl. Phys. Lett. 101, 112108 (2012); http://dx.doi.org/10.1063/1.4752165 (4 pages)

Online Publication Date: 14 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The degradation of CuInSe2 absorbers in ambient air is observed by the decay of the quasi-Fermi level splitting under well defined illumination with time. The decay is faster and stronger in absorbers with [Cu]/[In]<1 than in ones with a higher ratio. It can be attributed to the oxidation of the sample. Epitaxial films containing no Na show very similar trends, indicating that decay and oxidation are independent of the Na content. A standard CdS layer commonly used as buffer in solar cells, terminates the decay even over many months. Aged absorbers can be completely restored by a KCN etch.
Show PACS
68.55.ag Semiconductors
68.55.-a Thin film structure and morphology
81.15.Cd Deposition by sputtering
81.05.Hd Other semiconductors
81.65.Rv Passivation
81.65.Mq Oxidation
back to top
RSS Feeds

Magnetic force microscopy sensors providing in-plane and perpendicular sensitivity

T. Mühl, J. Körner, S. Philippi, C. F. Reiche, A. Leonhardt, and B. Büchner

Appl. Phys. Lett. 101, 112401 (2012); http://dx.doi.org/10.1063/1.4750058 (4 pages) | Cited 1 time

Online Publication Date: 10 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a bimodal magnetic force microscopy sensor consisting of a conventional cantilever beam, a spacer element, and an iron-filled carbon nanotube. Depending on the mode of the cantilever's resonant flexural vibration, the sensor is sensitive to magnetic field derivatives parallel and perpendicular to the sample's surface. This multifunctionality is supported by the scalar-type behavior of the magnetic monopole-like end of the iron-filled carbon nanotube.
Show PACS
07.79.Pk Magnetic force microscopes
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

Magnetic field dependence of the spin relaxation length in spin light-emitting diodes

Henning Höpfner, Carola Fritsche, Arne Ludwig, Astrid Ludwig, Frank Stromberg, Heiko Wende, Werner Keune, Dirk Reuter, Andreas D. Wieck, Nils C. Gerhardt, and Martin R. Hofmann

Appl. Phys. Lett. 101, 112402 (2012); http://dx.doi.org/10.1063/1.4752162 (4 pages) | Cited 1 time

Online Publication Date: 10 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the spin relaxation length during vertical electron transport in spin-light emitting diode devices as a function of magnetic field strength at room temperature. In most publications on spin relaxation in optoelectronic devices, strong magnetic fields are used to achieve perpendicular-to-plane magnetization of the spin injection contacts. We show experimentally that high magnetic field strengths significantly reduce spin relaxation during transport to the active region of the device. We obtain a spin relaxation length of 27(3) nm in magnetic remanence and at room temperature, which nearly doubles at 2 T magnetic field strength.
Show PACS
85.60.Jb Light-emitting devices

Digital magnetic heterostructures based on GaN using GGA-1/2 approach

J. P. T. Santos, M. Marques, L. G. Ferreira, R. R. Pelá, and L. K. Teles

Appl. Phys. Lett. 101, 112403 (2012); http://dx.doi.org/10.1063/1.4751285 (5 pages)

Online Publication Date: 10 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present ab-initio calculations of seven digital magnetic heterostructures, GaN δ-doped with V, Cr, Mn, Fe, Co, Ni, and Cu, forming two-dimensional systems. Only GaN δ-doped with V or Cr present a ferromagnetic ground state with high Curie temperatures. For both, to better describe the electronic properties, we used the GGA-1/2 approach. The ground state of GaN/Cr resulted in a two dimensional half-metal, with 100% spin polarization. For GaN/V, we obtained an insulating state: integer magnetic moment of 2.0 μB, a minority spin gap of 3.0 eV close to the gap of GaN, but a majority spin gap of 0.34 eV.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Pp Magnetic semiconductors
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
71.15.Qe Excited states: methodology

Thermalized ground state of artificial kagome spin ice building blocks

Unnar B. Arnalds, Alan Farhan, Rajesh V. Chopdekar, Vassilios Kapaklis, Ana Balan, Evangelos Th. Papaioannou, Martina Ahlberg, Frithjof Nolting, Laura J. Heyderman, and Björgvin Hjörvarsson

Appl. Phys. Lett. 101, 112404 (2012); http://dx.doi.org/10.1063/1.4751844 (4 pages) | Cited 4 times

Online Publication Date: 11 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a direct magnetic imaging study on the thermal macrospin ordering of artificial kagome spin ice building blocks. Using photoemission electron microscopy, employing x-ray magnetic circular dichroism, we are able to resolve the single domain magnetic nature of the macrospins and determine the states of the combined building block structures. The nano-patterning and material selection allows thermally activated magnetization reversal for the macrospins to occur. The ordering of the macrospins is dominated by the ground state, consistent with a thermal ground state ordering. This work paves the way for the realization of extended artificial spin ice structures exhibiting experimentally accessible thermal behavior.
Show PACS
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
79.60.-i Photoemission and photoelectron spectra
78.20.Ls Magneto-optical effects
75.60.Ch Domain walls and domain structure
75.60.Jk Magnetization reversal mechanisms

Giant coercivity in perpendicularly magnetized cobalt monolayer

D. C. Lin, C. Song, B. Cui, Y. Y. Wang, G. Y. Wang, and F. Pan

Appl. Phys. Lett. 101, 112405 (2012); http://dx.doi.org/10.1063/1.4752446 (4 pages)

Online Publication Date: 11 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report giant coercivity (HC) up to 35 kOe at 4 K, measured by the anomalous Hall effect, in perpendicularly magnetized Co (∼0.3 nm) films, where Co is approximately one monolayer. The HC is dramatically reduced with huge applied current, due to Joule heating rather than Rashba effect. It is also sensitive to temperatures, producing almost zero HC at 200 K. The Curie temperature of the Co monolayer is ∼275 K, far lower than that of bulk Co. The giant HC could be explained by the strong interaction at Co/Pd interface, providing a promising paradise: one monolayer, one permanent magnet.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
81.40.Gh Other heat and thermomechanical treatments
75.50.Vv High coercivity materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Fabricating high-density magnetic storage elements by low-dose ion beam irradiation

R. Neb, T. Sebastian, P. Pirro, B. Hillebrands, S. Pofahl, R. Schäfer, and B. Reuscher

Appl. Phys. Lett. 101, 112406 (2012); http://dx.doi.org/10.1063/1.4752447 (4 pages) | Cited 2 times

Online Publication Date: 14 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We fabricate magnetic storage elements by irradiating an antiferromagnetically coupled ferromagnetic/nonmagnetic/ferromagnetic trilayer by a low-dose ion beam. The irradiated areas become ferromagnetically coupled and are capable of storing information if their size is small enough. We employ Fe/Cr/Fe trilayers and a 30 keV focused Ga+-ion beam to demonstrate the working principle for a storage array with a bit density of 7  Gbit/in.2. Micromagnetic simulations suggest that bit densities of at least two magnitudes of order larger should be possible.
Show PACS
61.80.Jh Ion radiation effects
75.50.Ee Antiferromagnetics
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
back to top
RSS Feeds

Sub-micron normal-metal/insulator/superconductor tunnel junction thermometer and cooler using Nb

M. R. Nevala, S. Chaudhuri, J. Halkosaari, J. T. Karvonen, and I. J. Maasilta

Appl. Phys. Lett. 101, 112601 (2012); http://dx.doi.org/10.1063/1.4751355 (4 pages) | Cited 1 time

Online Publication Date: 10 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have fabricated Cu/AlOx-Al/Nb normal-metal/insulator/superconductor tunnel junction devices with a high value of the superconducting gap (up to ∼ 1 mV), using electron-beam lithography and angle evaporation techniques in the sub-micron scale. The subgap conductance of these junctions shows the expected strong temperature dependence, rendering them suitable for thermometry all the way from 100 mK to 6 K. In addition, some direct electronic cooling of the normal metal was also seen at bias values near the gap edge. The device performance was strongly influenced by the details of the Al layer geometry, with lateral spilling of the aluminium giving rise to strong extra subgap features, and the thickness of Al layer affecting the proximised superconducting gap value of the superconducting Al/Nb bilayer.
Show PACS
85.25.Am Superconducting device characterization, design, and modeling
07.20.Dt Thermometers

Proposal of terahertz patch antenna fed by intrinsic Josephson junctions

Hidehiro Asai, Masashi Tachiki, and Kazuo Kadowaki

Appl. Phys. Lett. 101, 112602 (2012); http://dx.doi.org/10.1063/1.4751846 (4 pages) | Cited 2 times

Online Publication Date: 11 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We propose a THz patch antenna, in which THz ac current is fed by intrinsic Josephson junctions (IJJs). The radiation power of the antenna for three different feed positions is calculated using the finite-difference time-domain method. We predict that the antenna will radiate sub-milliwatt terahertz waves with high radiation efficiency of over 20%. The maximum radiation power will depend on the position of the feed. We also show that the radiation characteristics of the antenna are described well by the equivalent inductance-capacitance-resistance circuit model.
Show PACS
84.40.Ba Antennas: theory, components and accessories
85.25.Cp Josephson devices
02.70.Bf Finite-difference methods

Superconducting detector dynamics studied by quantum pump-probe spectroscopy

Reinier W. Heeres and Valery Zwiller

Appl. Phys. Lett. 101, 112603 (2012); http://dx.doi.org/10.1063/1.4750139 (4 pages) | Cited 1 time

Online Publication Date: 11 September 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We explore the dynamics of superconducting single-photon detectors (SSPDs) on the picosecond time-scale using a correlated photon-pair source based on spontaneous parametric downconversion (SPDC), corresponding to a pump-probe experiment at the single-photon level. We show that the detector can operate in a regime where the two-photon detection probability is orders of magnitude larger than the single-photon detection probability. The characteristic relaxation time-scale of the out-of-equilibrium hot-spot is found to be ∼ 15 ps. Our measurement technique is an effective tool to study fast two-photon processes, without requiring a power-dependence measurements to determine the number of photons involved.
Show PACS
85.25.Oj Superconducting optical, X-ray, and γ-ray detectors (SIS, NIS, transition edge)
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
Page 2 of 5 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close