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10 May 2010

Volume 96, Issue 19, Articles (19xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 96, 193101 (2010); http://dx.doi.org/10.1063/1.3425776 (3 pages)

J. J. Zhang, N. Hrauda, H. Groiss, A. Rastelli, J. Stangl, F. Schäffler, O. G. Schmidt, and G. Bauer
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Thin-film transistors based on p-type Cu2O thin films produced at room temperature

Elvira Fortunato, Vitor Figueiredo, Pedro Barquinha, Elangovan Elamurugu, Raquel Barros, Gonçalo Gonçalves, Sang-Hee Ko Park, Chi-Sun Hwang, and Rodrigo Martins

Appl. Phys. Lett. 96, 192102 (2010); http://dx.doi.org/10.1063/1.3428434 (3 pages) | Cited 7 times

Online Publication Date: 10 May 2010

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Copper oxide (Cu2O) thin films were used to produce bottom gate p-type transparent thin-film transistors (TFTs). Cu2O was deposited by reactive rf magnetron sputtering at room temperature and the films exhibit a polycrystalline structure with a strongest orientation along (111) plane. The TFTs exhibit improved electrical performance such as a field-effect mobility of 3.9 cm2/V s and an on/off ratio of 2×102.
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85.30.Tv Field effect devices
85.40.Sz Deposition technology
81.15.Cd Deposition by sputtering
73.50.Dn Low-field transport and mobility; piezoresistance

Thermal shot noise in top-gated single carbon nanotube field effect transistors

J. Chaste, E. Pallecchi, P. Morfin, G. Fève, T. Kontos, J.-M. Berroir, P. Hakonen, and B. Plaçais

Appl. Phys. Lett. 96, 192103 (2010); http://dx.doi.org/10.1063/1.3425889 (3 pages) | Cited 2 times

Online Publication Date: 11 May 2010

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The high-frequency transconductance and current noise of top-gated single carbon nanotube transistors have been measured and used to investigate hot electron effects in one-dimensional transistors. Results are in good agreement with a theory of one-dimensional nanotransistor. In particular the prediction of a large transconductance correction to the Johnson–Nyquist thermal noise formula is confirmed experimentally. Experiment shows that nanotube transistors can be used as fast charge detectors for quantum coherent electronics with a resolution of 13 μe/math in the 0.2–0.8 GHz band.
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85.30.Tv Field effect devices
85.40.Qx Microcircuit quality, noise, performance, and failure analysis
85.35.Kt Nanotube devices

High-temperature electrical transport behaviors of the layered Ca2Co2O5-based ceramics

Jinle Lan, Yuan-Hua Lin, Guo-jing Li, Shaoliang Xu, Yong Liu, Ce-Wen Nan, and Shu-Jin Zhao

Appl. Phys. Lett. 96, 192104 (2010); http://dx.doi.org/10.1063/1.3425891 (3 pages) | Cited 5 times

Online Publication Date: 11 May 2010

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Textured Bi-substituted Ca2Co2O5 ceramics have been prepared using a coprecipitation method combined with spark plasma sintering. The Bi substitution is effective in increasing the grain orientation of the Ca2Co2O5-based ceramics (from 0.46 to 0.85). Electrical conductivity increases obviously with partial substitution of Bi3+ for Ca2+ (from 113.9 to 142.4 S/cm at 973 K). The Ca1.92Bi0.08Co2O5 sample exhibits higher power factor (4.4×10−4 W m−1 K−2) than that of pure Ca2Co2O5 (3.2×10−4 W m−1 K−2) at 973 K, indicating that the Ca2Co2O5 system is another promising p-type material for high-temperature thermoelectric applications.
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72.20.Pa Thermoelectric and thermomagnetic effects
72.20.Fr Low-field transport and mobility; piezoresistance
72.80.Sk Insulators

Selective atomic layer deposition of HfO2 on copper patterned silicon substrates

Qian Tao, Gregory Jursich, and Christos Takoudis

Appl. Phys. Lett. 96, 192105 (2010); http://dx.doi.org/10.1063/1.3428771 (3 pages) | Cited 2 times

Online Publication Date: 11 May 2010

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Selective atomic layer deposition (ALD) was performed on copper patterned silicon substrates to selectively deposit HfO2 film on silicon. The selectivity is based on differences of surface physics/chemistry rather than use of any molecular masking such as self-assembled monolayers. On silicon, the growth rate of HfO2 is 0.11 nm /cycle with no initial inhibition of film growth, while on copper no HfO2 deposition was observed up to at least 25 ALD cycles. The selective growth on silicon over copper at 25 ALD cycles provides a patterned film deposition at thicknesses of 2.8 nm HfO2 which is relevant to semiconductor nanofabrication.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
68.55.aj Insulators
78.66.Nk Insulators
77.55.-g Dielectric thin films
79.60.Dp Adsorbed layers and thin films

Charge detrapping and dielectric breakdown of nanocrystalline zinc oxide embedded zirconium-doped hafnium oxide high-k dielectrics for nonvolatile memories

Chia-Han Yang, Yue Kuo, and Chen-Han Lin

Appl. Phys. Lett. 96, 192106 (2010); http://dx.doi.org/10.1063/1.3429590 (3 pages) | Cited 3 times

Online Publication Date: 12 May 2010

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Charge detrapping and dielectric breakdown phenomena of the nanocrystalline zinc oxide embedded zirconium-doped hafnium oxide high-k dielectric have been investigated. Charges were loosely or strongly retained at the nanocrystal sites which were saturated above a certain stress voltage. From the polarity change of the relaxation current, it was confirmed that the high-k part of the dielectric film was broken under a high gate bias voltage condition while the nanocrystals still retained charges. These charges were gradually released. These unique characteristics are important to the performance and reliability of the memory device.
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77.22.Jp Dielectric breakdown and space-charge effects
73.40.-c Electronic transport in interface structures
77.55.D- High-permittivity gate dielectric films
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Nanoscale chemical state analysis of resistance random access memory device reacting with Ti

Hisashi Shima, Takashi Nakano, and Hiro Akinaga

Appl. Phys. Lett. 96, 192107 (2010); http://dx.doi.org/10.1063/1.3373594 (3 pages) | Cited 3 times

Online Publication Date: 12 May 2010

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The thermal stability of the resistance random access memory material in the reducing atmosphere at the elevated temperature was improved by the addition of Ti. The unipolar resistance switching before and after the postdeposition annealing (PDA) process at 400 °C was confirmed in Pt/CoO/Ti(5 nm)/Pt device, while the severe degradation of the initial resistance occurs in the Pt/CoO/Pt and Pt/CoO/Ti(50 nm)/Pt devices. By investigating the chemical bonding states of Co, O, and Ti using electron energy loss spectroscopy combined with transmission electron microscopy, it was revealed that excess Ti induces the formation of metallic Co, while the thermal stability was improved by trace Ti. Moreover, it was indicated that the filamentary conduction path can be thermally induced after PDA in the oxide layer by analyzing electrical properties of the degraded devices. The adjustment of the reducing elements is quite essential in order to participate in their profits.
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84.30.Sk Pulse and digital circuits

p-type conduction in sputtered indium oxide films

Jolanta Stankiewicz, Francisco Villuendas, and Rafael Alcalá

Appl. Phys. Lett. 96, 192108 (2010); http://dx.doi.org/10.1063/1.3430035 (3 pages) | Cited 6 times

Online Publication Date: 12 May 2010

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We report p-type conductivity in intrinsic indium oxide (IO) films deposited by magnetron sputtering on fused quartz substrates under oxygen-rich ambient. Highly oriented (111) films were studied by x-ray diffraction, optical absorption, and Hall effect measurements. We fabricated p-n homojunctions on these films.
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73.61.Le Other inorganic semiconductors
78.66.Li Other semiconductors
81.15.Cd Deposition by sputtering
72.20.My Galvanomagnetic and other magnetotransport effects
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
78.40.Fy Semiconductors

Two-dimensional electron or hole gas at ZnO/6H-SiC interface

Y. H. Lu, B. Xu, R. Q. Wu, and Y. P. Feng

Appl. Phys. Lett. 96, 192109 (2010); http://dx.doi.org/10.1063/1.3425667 (3 pages)

Online Publication Date: 12 May 2010

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Electronic structures of ZnO(0001)/6H-SiC(0001) interfaces are investigated using first-principles method. Two-dimensional charge carriers are found at the interfaces. Depending on the interface structure, the type of charge carriers can be n-type if oxygen terminated ZnO(0001) is grown on SiC and p-type when the interface is formed with Zn-terminated ZnO and C-terminated SiC. The interface formed with Zn-terminated ZnO and Si-terminated SiC is found to be half-metallic. Intrinsic charge carriers at the interface of the two wide gap semiconductors could be useful for future oxide-based electronics and spintronics.
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71.20.Nr Semiconductor compounds
73.20.At Surface states, band structure, electron density of states
71.15.-m Methods of electronic structure calculations
68.35.Ct Interface structure and roughness
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Group-II acceptors in wurtzite AlN: A screened hybrid density functional study

Áron Szabó, Ngyen Tien Son, Erik Janzén, and Adam Gali

Appl. Phys. Lett. 96, 192110 (2010); http://dx.doi.org/10.1063/1.3429086 (3 pages) | Cited 5 times

Online Publication Date: 12 May 2010

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We systematically studied the group-II acceptors in wurtzite AlN by screened hybrid density functional calculations. We show that the shallowest isolated group-II substitutional defect is Mg, while codoping of Mg and O may yield even shallower acceptor level.
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71.55.Eq III-V semiconductors
61.72.uj III-V and II-VI semiconductors
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

Transport properties of LaTiO3/SrTiO3 heterostructures

R. Ohtsuka, M. Matvejeff, K. Nishio, R. Takahashi, and M. Lippmaa

Appl. Phys. Lett. 96, 192111 (2010); http://dx.doi.org/10.1063/1.3430006 (3 pages) | Cited 5 times

Online Publication Date: 13 May 2010

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Resistivity measurements show that SrTiO3/LaTiO3/SrTiO3 heterostructures remain metallic even for single unit cell LaTiO3 layers. Hall resistances of all heterostructures are nonlinear functions of the applied field. The Hall data is analyzed in terms of a two-layer model, indicating that a low-mobility layer exists at the LaTiO3/SrTiO3 interface, while carriers with mobilities approaching 10 000 cm2/V s are present deep in the SrTiO3 substrate.
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73.40.-c Electronic transport in interface structures
72.20.Ht High-field and nonlinear effects
72.80.Sk Insulators
72.20.My Galvanomagnetic and other magnetotransport effects

Spin-filtering transport and switching effect of MnCu single-molecule magnet

H. Hao, X. H. Zheng, Z. X. Dai, and Z. Zeng

Appl. Phys. Lett. 96, 192112 (2010); http://dx.doi.org/10.1063/1.3430063 (3 pages) | Cited 7 times

Online Publication Date: 13 May 2010

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Electron transport of a single-molecule magnet (SMM) device has been investigated using the first-principles calculations. The SMM based device is constructed by a SMM MnCu [MnCuCl(5-Br-sap)2(MeOH)] bridged between semi-infinite Au(100) electrodes with thiol groups connecting the molecule and the gold electrodes. Our results exhibit crucial features of spin filtering and Kondo resonance. The spin filtering remains robust, whereas the Kondo resonance highly depends on the contact geometry. Specifically, this Kondo resonance can be switched on or off by changing the contact distance. The mechanisms of these features are formulated in details.
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75.50.Xx Molecular magnets
85.65.+h Molecular electronic devices
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
72.25.-b Spin polarized transport
72.10.Fk Scattering by point defects, dislocations, surfaces, and other imperfections (including Kondo effect)

Electrode dependence of resistive switching in Mn-doped ZnO: Filamentary versus interfacial mechanisms

H. Y. Peng, G. P. Li, J. Y. Ye, Z. P. Wei, Z. Zhang, D. D. Wang, G. Z. Xing, and T. Wu

Appl. Phys. Lett. 96, 192113 (2010); http://dx.doi.org/10.1063/1.3428365 (3 pages) | Cited 29 times

Online Publication Date: 13 May 2010

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We carry out a comparative study on resistive switching in Mn-doped ZnO thin films; samples grown on Pt and Si show unipolar and bipolar switching behaviors, respectively. Fittings of the current-voltage curves and area dependence of the device resistance reveal the filamentary conduction in Pt/Mn:ZnO/Pt. On the other hand, the interfacial effect dominates in Pt/Mn:ZnO/Si, and its low resistance state exponentially relaxes toward the high resistance state in contrast to the good data retention in Pt/Mn:ZnO/Pt. Our results suggest that selecting electrodes dictates the resistive switching mechanism presumably by affecting the migration dynamics of oxygen vacancies.
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73.40.Ns Metal-nonmetal contacts
73.40.Sx Metal-semiconductor-metal structures
73.61.Ga II-VI semiconductors
72.60.+g Mixed conductivity and conductivity transitions
61.72.jd Vacancies
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Physical and chemical characterization of combinatorial metal gate electrode Ta–C–N library film

K.-S. Chang, M. L. Green, I. Levin, J. R. Hattrick-Simpers, C. Jaye, D. A. Fischer, I. Takeuchi, and S. De Gendt

Appl. Phys. Lett. 96, 192114 (2010); http://dx.doi.org/10.1063/1.3428788 (3 pages) | Cited 4 times

Online Publication Date: 13 May 2010

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This paper reports comprehensive structural and chemical analyses for the combinatorial Ta–C–N/HfO2 system, crucial data for understanding the electrical properties of Ta–C–N/HfO2. Combinatorial Ta–C–N “library” (composition spread) films were deposited by magnetron sputtering. Electron probe wavelength dispersive spectroscopy and x-ray fluorescence-yield near-edge spectroscopy were used to quantitatively determine the composition across these films. Scanning x-ray microdiffractometry determined that a solid solution of Ta(C,N)x forms and extends to compositions (0.3 ≤ Ta ≤ 0.5 and 0.57 ≤ Ta ≤ 0.67) that were previously unknown. The thermal stability of the Ta–C–N/HfO2 library was studied using high resolution transmission electron microscopy, which shows Ta–C–N/HfO2/SiO2/Si exhibiting good thermal stability up to 950 °C.
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68.55.A- Nucleation and growth
68.60.Dv Thermal stability; thermal effects
77.55.D- High-permittivity gate dielectric films
81.15.Cd Deposition by sputtering

High-mobility low-temperature ZnO transistors with low-voltage operation

Hyojin Bong, Wi Hyoung Lee, Dong Yun Lee, Beom Joon Kim, Jeong Ho Cho, and Kilwon Cho

Appl. Phys. Lett. 96, 192115 (2010); http://dx.doi.org/10.1063/1.3428357 (3 pages) | Cited 17 times

Online Publication Date: 14 May 2010

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Low voltage high mobility n-type thin film transistors (TFTs) based on sol-gel processed zinc oxide (ZnO) were fabricated using a high capacitance ion gel gate dielectric. The ion gel gated solution-processed ZnO TFTs were found to exhibit excellent electrical properties. TFT carrier mobilities were 13 cm2/V s, ON/OFF current ratios were 105, regardless of the sintering temperature used for the preparation of the ZnO thin films. Ion gel gated ZnO TFTs are successfully demonstrated on plastic substrates for the large area flexible electronics.
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85.30.Tv Field effect devices
81.10.Dn Growth from solutions
81.10.Fq Growth from melts; zone melting and refining
81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
82.70.Gg Gels and sols
73.50.Dn Low-field transport and mobility; piezoresistance
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Vortex manipulation in a superconducting matrix with view on applications

M. V. Milošević and F. M. Peeters

Appl. Phys. Lett. 96, 192501 (2010); http://dx.doi.org/10.1063/1.3425672 (3 pages) | Cited 2 times

Online Publication Date: 10 May 2010

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We show how a single flux quantum can be effectively manipulated in a superconducting film with a matrix of blind holes. Such a sample can serve as a basic memory element, where the position of the vortex in a k×l matrix of pinning sites defines the desired combination of n bits of information (2n = k×l). Vortex placement is achieved by strategically applied current and the resulting position is read out via generated voltage between metallic contacts on the sample. Such a device can also act as a controllable source of a nanoengineered local magnetic field for, e.g., spintronics applications.
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74.78.-w Superconducting films and low-dimensional structures
74.25.Wx Vortex pinning (includes mechanisms and flux creep)
85.25.Hv Superconducting logic elements and memory devices; microelectronic circuits

Flexural deformation in a compositionally stepped ferrite and magnetoelectric effects in a composite with piezoelectrics

S. K. Mandal, G. Sreenivasulu, V. M. Petrov, and G. Srinivasan

Appl. Phys. Lett. 96, 192502 (2010); http://dx.doi.org/10.1063/1.3428774 (3 pages) | Cited 13 times

Online Publication Date: 10 May 2010

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The nature of strain mediated magnetoelectric (ME) coupling is investigated in laminates of lead zirconate titanate (PZT) and compositionally stepped ferrite with grading of piezomagnetic coefficient. ME effects that could only be attributed to grading related bending strain are observed in a trilayer of ferrite and oppositely poled PZT. It is shown that in a bilayer, grading induced flexural strain counteracts bending moment due to structural asymmetry and enhances ME coupling by a factor of 2. A zero-bias field ME effect is observed in such laminates. The graded composites are of interest for self-biased magnetic field sensors.
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81.40.Lm Deformation, plasticity, and creep
75.85.+t Magnetoelectric effects, multiferroics
75.50.Gg Ferrimagnetics
75.80.+q Magnetomechanical effects, magnetostriction
77.84.Cg PZT ceramics and other titanates
77.65.Ly Strain-induced piezoelectric fields

The effect of trapping superparamagnetic beads on domain wall motion

Matthew T. Bryan, Julian Dean, Thomas Schrefl, Faye E. Thompson, John Haycock, and Dan A. Allwood

Appl. Phys. Lett. 96, 192503 (2010); http://dx.doi.org/10.1063/1.3428775 (3 pages) | Cited 9 times

Online Publication Date: 10 May 2010

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Domain walls may act as localized field sources to trap and move superparamagnetic beads for manipulating biological cells and DNA. The interaction between beads of various diameters and a wall is investigated using a combination of micromagnetic and analytical models. Domain walls can transport beads under applied magnetic fields but the mutual attraction between the bead and wall causes drag forces affecting the bead to couple into the wall motion. Therefore, the interaction with the bead causes a fundamental change in the domain wall dynamics, reducing the wall mobility by five orders of magnitude.
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87.17.-d Cell processes
87.16.-b Subcellular structure and processes
87.14.gk DNA

Electric-field-control of magnetic remanence of NiFe2O4 thin film epitaxially grown on Pb(Mg1/3Nb2/3)O3–PbTiO3

Jung Hwan Park, Young Kyu Jeong, Sangwoo Ryu, Jong Yeog Son, and Hyun Myung Jang

Appl. Phys. Lett. 96, 192504 (2010); http://dx.doi.org/10.1063/1.3427311 (3 pages) | Cited 5 times

Online Publication Date: 11 May 2010

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We propose an asymmetric bilayer structure in which the magnetic remanence (MR) is controlled by the in-plane strain of the top NiFe2O4 (NFO) layer epitaxially constrained by the bottom Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) substrate. In this asymmetric structure, an electric-field-induced giant piezoelectric strain from the bottom PMN-PT layer is effectively transferred to the top NFO layer. We have shown that the room-temperature magnetic remanence (MR) of the 100-nm-thick NFO layer is enhanced by 46% when an electric-field-induced in-plane compressive strain is about −0.1%. Synchrotron x-ray absorption near edge structure study supports a scenario of the cation-charge redistribution between Ni2+ and Fe3+ ions under the condition of an electric-field-induced in-plane compressive strain.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
68.60.Bs Mechanical and acoustical properties
75.80.+q Magnetomechanical effects, magnetostriction
77.65.Ly Strain-induced piezoelectric fields
78.70.Dm X-ray absorption spectra
75.70.Ak Magnetic properties of monolayers and thin films

Neutron scattering measurements of magnetic excitations in Gd/Y superlattices

A. T. D. Grünwald, A. R. Wildes, W. Schmidt, E. V. Tartakovskaya, G. Nowak, K. Theis-Bröhl, and A. Schreyer

Appl. Phys. Lett. 96, 192505 (2010); http://dx.doi.org/10.1063/1.3428425 (3 pages)

Online Publication Date: 12 May 2010

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Neutron inelastic scattering has been used to measure the magnetic excitations as a function of applied magnetic field in an antiferromagnetically coupled Gd/Y superlattice. The excitations were measured along the c-axis, which is parallel to the normal of the interfaces and the sample growth direction. Dispersive spin waves were unambiguously detected on the application of a magnetic field. The spin waves are shown to renormalize with field following a basic model drawn from standard spin wave theory. The model required no free parameters aside from an initial amplitude.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Ee Antiferromagnetics
75.30.Ds Spin waves
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance

Simulation of magnetization switching by electric-field manipulation of magnetic anisotropy

D. Chiba, Y. Nakatani, F. Matsukura, and H. Ohno

Appl. Phys. Lett. 96, 192506 (2010); http://dx.doi.org/10.1063/1.3428959 (3 pages) | Cited 10 times

Online Publication Date: 12 May 2010

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Electrical anisotropy modulation was recently observed in ferromagnetic semiconductors and metals. The authors have investigated magnetization switching through magnetic anisotropy modulation induced by external electric field by means of simulation. Macrospin simulation using Landau–Lifshitz–Gilbert equation shows that switching is possible by controlling magnetic anisotropy for appropriate sets of parameters. The condition for quasistatic magnetization switching is also presented, in which magnetization direction is determined to minimize the magnetic free energy.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Gw Magnetic anisotropy
75.50.Pp Magnetic semiconductors
75.50.Dd Nonmetallic ferromagnetic materials

Tunnel magnetoresistance properties and film structures of double MgO barrier magnetic tunnel junctions

H. D. Gan, S. Ikeda, W. Shiga, J. Hayakawa, K. Miura, H. Yamamoto, H. Hasegawa, F. Matsukura, T. Ohkubo, K. Hono, and H. Ohno

Appl. Phys. Lett. 96, 192507 (2010); http://dx.doi.org/10.1063/1.3429594 (3 pages) | Cited 14 times

Online Publication Date: 13 May 2010

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The authors fabricated double MgO barrier magnetic tunnel junctions (MTJs) with 3-nm-thick Co40Fe40B20 free layer. When annealed at 350 °C, tunnel magnetoresistance (TMR) ratio at room temperature was 130%, much lower than that (297%) of single MgO barrier MTJs processed and annealed under the same condition. The middle CoFeB free layer sandwiched between the two MgO barriers was found to be mostly amorphous. Replacement of the Co40Fe40B20 free layer by a highly oriented Co50Fe50 layer and a composite Co50Fe50/Co40Fe40B20 layer led to the enhanced TMR ratios up to 165% and 212% at annealing temperature of 350 °C, respectively.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.Pq Other materials
81.40.Gh Other heat and thermomechanical treatments
81.40.Rs Electrical and magnetic properties related to treatment conditions

Current-induced switching of magnetic vortex core in ferromagnetic elliptical disks

Keisuke Yamada, Shinya Kasai, Yoshinobu Nakatani, Kensuke Kobayashi, and Teruo Ono

Appl. Phys. Lett. 96, 192508 (2010); http://dx.doi.org/10.1063/1.3428792 (3 pages) | Cited 3 times

Online Publication Date: 13 May 2010

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We report the experimental observation and micromagnetics simulation of the current-induced switching of the magnetic vortex core in ferromagnetic elliptical disks. We found that the critical current density required for the core switching depends on the relative alignment between the current direction and the elliptical axes of the disk. The micromagnetics simulation results qualitatively reproduce the experimental findings, suggesting that the vortex core displacement induced by the current plays a significant role for the core switching rather than the core velocity.
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85.70.Li Other magnetic recording and storage devices (including tapes, disks, and drums)

Nonlocal injection of spin current into a superconducting Nb wire

K. Ohnishi, T. Kimura, and Y. Otani

Appl. Phys. Lett. 96, 192509 (2010); http://dx.doi.org/10.1063/1.3427483 (3 pages) | Cited 1 time

Online Publication Date: 14 May 2010

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Pure spin current injection into a superconductive Nb was demonstrated experimentally by employing a nonlocal spin absorption technique in a multiterminal lateral structure. From the reduction in spin signals, we found the absorption efficiency remained almost unchanged even after superconducting transition. The Nb/Cu interface properties were also complementarily examined by using a Nb/Cu/Nb junction incorporated in the same device, revealing superconductivity below the transition temperature. These experimental results support that the pure spin current can be absorbed into a superconductive Nb wire with almost the same efficiency as in a normal state.
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84.71.Mn Superconducting wires, fibers, and tapes
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.45.+c Proximity effects; Andreev reflection; SN and SNS junctions
85.25.Cp Josephson devices
72.25.-b Spin polarized transport
74.25.F- Transport properties

Controllable magnetic property of SiC by anion-cation codoping

Hui Pan, Yong-Wei Zhang, Vivek Shenoy, and Huajian Gao

Appl. Phys. Lett. 96, 192510 (2010); http://dx.doi.org/10.1063/1.3428428 (3 pages) | Cited 5 times

Online Publication Date: 14 May 2010

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We present that the magnetic property of SiC can be controlled by anion-cation codoping based on first-principles calculations. The anion-cation codoped SiC can be either ferromagnetic or antiferromagnetic by controlling the codoping configurations. The Ferromagnetic SiC with a high exchange energy can be achieved by nitrogen-transition metal (TM: Cr, Mn, Fe, and Co) codoping, while oxygen-TM codoped SiC is antiferromagnetic or non-magnetic, regardless of whether TM-doped SiC is ferromagnetic, antiferromagnetic, or nonmagnetic. The ferromagnetism was attributed to carrier-mediated interactions because of the coupling between the spin-polarized d and p electrons.
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75.30.Et Exchange and superexchange interactions
75.50.Dd Nonmetallic ferromagnetic materials
75.50.Ee Antiferromagnetics
61.72.up Other materials
75.76.+j Spin transport effects
72.25.Dc Spin polarized transport in semiconductors
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Tunable band gap in Bi(Fe1−xMnx)O3 films

X. S. Xu, J. F. Ihlefeld, J. H. Lee, O. K. Ezekoye, E. Vlahos, R. Ramesh, V. Gopalan, X. Q. Pan, D. G. Schlom, and J. L. Musfeldt

Appl. Phys. Lett. 96, 192901 (2010); http://dx.doi.org/10.1063/1.3427499 (3 pages) | Cited 6 times

Online Publication Date: 10 May 2010

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In order to investigate band gap tunability in polar oxides, we measured the optical properties of a series of Bi(Fe1−xMnx)O3 thin films. The absorption response of the mixed metal solid solutions is approximately a linear combination of the characteristics of the two end members, a result that demonstrates straightforward band gap tunability in this system.
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68.55.-a Thin film structure and morphology
78.66.-w Optical properties of specific thin films
71.20.-b Electron density of states and band structure of crystalline solids
78.20.-e Optical properties of bulk materials and thin films
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