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

7 Mar 2011

Volume 98, Issue 10, Articles (10xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 98, 104101 (2011); http://dx.doi.org/10.1063/1.3560505 (3 pages)

Zhongchang Wang, Susumu Tsukimoto, Rong Sun, Mitsuhiro Saito, and Yuichi Ikuhara
Enlarge Image | Read More
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Low temperature reflectivity study of nonpolar ZnO/(Zn,Mg)O quantum wells grown on M-plane ZnO substrates

L. Béaur, T. Bretagnon, C. Brimont, T. Guillet, B. Gil, D. Tainoff, M. Teisseire, and J.-M. Chauveau

Appl. Phys. Lett. 98, 101913 (2011); http://dx.doi.org/10.1063/1.3565969 (3 pages) | Cited 4 times

Online Publication Date: 11 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report growth of high quality ZnO/Zn0.8Mg0.2O quantum wells on M-plane oriented ZnO substrates. The optical properties are studied by reflectance spectroscopy. The optical spectra reveal strong in-plane optical anisotropies, as predicted by group theory, and clear reflectance structures, as an evidence of good interface morphologies. Signatures of confined excitons built from spin-orbit split-off valence band, analogous to C-exciton in bulk ZnO, are detected using a light polarized along the c-axis. Experiments performed in orthogonal polarization, show confined states analogous to A and B bulk excitons. Envelope function calculations including excitonic interaction nicely match the experimental results.
Show PACS
81.07.St Quantum wells
81.05.Dz II-VI semiconductors
73.21.Fg Quantum wells
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.35.-y Excitons and related phenomena
78.67.De Quantum wells
back to top
RSS Feeds

Surface band bending and electron affinity as a function of hole accumulation density in surface conducting diamond

M. T. Edmonds, C. I. Pakes, S. Mammadov, W. Zhang, A. Tadich, J. Ristein, and L. Ley

Appl. Phys. Lett. 98, 102101 (2011); http://dx.doi.org/10.1063/1.3561760 (3 pages) | Cited 4 times

Online Publication Date: 7 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Simultaneous measurements of work function (ϕ) and C 1s core level shift were employed to determine the change in electron affinity (χ) and band bending as a function of hole sheet density on H-terminated diamond for atmospheric and fullerene (C60F48) induced surface conductivity. Contrary to earlier investigations, it is shown that changes in work function do not reflect variations in the position of the surface Fermi level in response to surface transfer doping. Instead, with a transition from −0.96 to −0.33 eV, χ accounts for a significant amount of the change in ϕ for hole densities between 5×108 and 4×1013 cm−2.
Show PACS
73.20.At Surface states, band structure, electron density of states
73.30.+y Surface double layers, Schottky barriers, and work functions
73.25.+i Surface conductivity and carrier phenomena
81.05.ug Diamond

Nonlinear transport properties and Joule heating effect in charge ordered LuFe2O4

S. Cao, J. Li, H. F. Tian, Y. B. Qin, L. J. Zeng, H. X. Yang, and J. Q. Li

Appl. Phys. Lett. 98, 102102 (2011); http://dx.doi.org/10.1063/1.3562314 (3 pages) | Cited 3 times

Online Publication Date: 7 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The nonlinear current-voltage (I-V) relation of charge ordered (CO) LuFe2O4 has been studied in the temperature range from 220 to 520 K. Strong nonlinear effects are identified in the CO state and disappear in high-temperature charge disordered state. Alternation of the CO state under applied electric field is directly revealed by in situ transmission electron microscopy observations. Careful investigations of time-dependent resistance under the applied electric field near the threshold value (Eth) often show three distinct steps for the nonlinear transitions. The CO collapse likely at a critical conductivity yields a sharp drop in resistance.
Show PACS
72.60.+g Mixed conductivity and conductivity transitions
72.80.Sk Insulators
66.70.Lm Other systems such as ionic crystals, molecular crystals, nanotubes, etc.

Photocarrier relaxation through the manifold of localized states in a polymer-fullerene bulk heterojunction material

Nelson E. Coates, Daniel Moses, and Alan J. Heeger

Appl. Phys. Lett. 98, 102103 (2011); http://dx.doi.org/10.1063/1.3562371 (3 pages) | Cited 2 times

Online Publication Date: 7 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the transport and relaxation of photogenerated carriers in a polymer-fullerene bulk-heterojunction (BHJ) material by measuring the transient photoconductivity as a function of the sample temperature. Data in the nanosecond time regime indicate that following the initial trapping (within ∼ 100 ps), the photogenerated carriers relax into the manifold of disorder-induced localized states near the band edge, and the transport becomes thermally activated. By measuring the temporal dependence of the transport activation energy, we are able to monitor the relaxation of carriers into deeper traps, with a corresponding reduction in carrier mobility. A comparison of BHJs made from different molecular weight poly(3-hexylthiophene) (P3HT) (21 and 95 kDa), indicates that higher molecular weight polymer in the BHJ material yields a consistently higher activation energy. The reduction in the carrier mobility in BHJ materials made with higher molecular weight P3HT is confirmed by steady-state photoconductivity measurements. In contrast to disordered inorganic semiconductors (e.g., amorphous silicon), the activation energies associated with the density of states in the disorder-induced band tails are a small fraction (<10%) of the band gap energy of P3HT.
Show PACS
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.40.+w Photoconduction and photovoltaic effects
72.20.Fr Low-field transport and mobility; piezoresistance
73.40.-c Electronic transport in interface structures

Influence of electric field on persistent photoconductivity in unintentionally doped n-type GaN

Qifeng Hou, Xiaoliang Wang, Hongling Xiao, Cuimei Wang, Cuibai Yang, Haibo Yin, Qingwen Deng, Jinmin Li, Zhanguo Wang, and Xun Hou

Appl. Phys. Lett. 98, 102104 (2011); http://dx.doi.org/10.1063/1.3562008 (3 pages)

Online Publication Date: 8 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The influence of electric field on persistent photoconductivity in unintentionally doped n-GaN is investigated. It was found that under higher electric field the build-up course was slowed down while the decay course was accelerated. After a higher-voltage pulse, it was observed that the current dropped to a value lower than the dark current, and a current increase that lasted for thousands of seconds was observed. It is suggested that the above phenomena should be caused by the increase in capture rate of electron traps with electric field and are related to the Coulomb-repulsive characteristic of defects related to persistent photoconductivity.
Show PACS
72.40.+w Photoconduction and photovoltaic effects
73.23.Hk Coulomb blockade; single-electron tunneling
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
81.05.Ea III-V semiconductors
72.80.Ey III-V and II-VI semiconductors

Charge transfer dynamics in Cu-doped ZnO nanowires

Guozhong Xing, Guichuan Xing, Mingjie Li, Edbert Jarvis Sie, Dandan Wang, Arief Sulistio, Quan-lin Ye, Cheng Hon Alfred Huan, Tom Wu, and Tze Chien Sum

Appl. Phys. Lett. 98, 102105 (2011); http://dx.doi.org/10.1063/1.3558912 (3 pages) | Cited 11 times

Online Publication Date: 8 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Time resolved photoluminescence (TRPL) and transient absorption (TA) spectroscopy reveal an ultrafast charge transfer (CT) process, with an electron localization time constant 39±9 ps, between the ZnO host and the Cu dopants in Cu-doped ZnO nanowires. This CT process effectively competes with the ZnO band edge emission, resulting in the quenching of the ZnO UV emission. TRPL measurements show that the UV decay dynamics coincides with the buildup of the Cu-related green emission. TA measurements probing the state-filling of the band edge and defect states provide further support to the CT model where the bleaching dynamics concur with the TRPL lifetimes.
Show PACS
73.63.Nm Quantum wires
78.67.Lt Quantum wires
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.55.Et II-VI semiconductors
71.55.Gs II-VI semiconductors
78.67.Uh Nanowires

Thin-film transistors based on poly(3,3‴-dialkyl-quarterthiophene) and zinc oxide nanowires with improved ambient stability

Sara M. C. Vieira, Gen-Wen Hsieh, Husnu E. Unalan, Sefa Dag, Gehan A. J. Amaratunga, and William I. Milne

Appl. Phys. Lett. 98, 102106 (2011); http://dx.doi.org/10.1063/1.3560982 (3 pages) | Cited 1 time

Online Publication Date: 9 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The ambient stability of thin-film transistors (TFTs) based on zinc oxide (ZnO) nanowires embedded in poly(3,3‴-dialkyl-quarterthiophene) was monitored through time dependence of electrical characteristics over a period of 16 months. The hybrid-based TFT showed an initial hole mobility in the linear regime of 4.2×10−4 cm2/V s. After 16 months storage in ambient conditions (exposed to air, moisture, and light) the mobility decreased to 2.3×10−5 cm2/V s. Comparatively the organic-based TFT lost total carrier mobility after one month storage making the hybrid-based TFTs more suitable for transistor applications when improved stability combined with structural flexibility are required.
Show PACS
85.30.Tv Field effect devices
81.05.Dz II-VI semiconductors
81.07.Gf Nanowires

Correlation of photoconductivity response of amorphous In–Ga–Zn–O films with transistor performance using microwave photoconductivity decay method

Satoshi Yasuno, Toshihiro Kugimiya, Shinya Morita, Aya Miki, Futoshi Ojima, and Shingo Sumie

Appl. Phys. Lett. 98, 102107 (2011); http://dx.doi.org/10.1063/1.3561755 (3 pages) | Cited 5 times

Online Publication Date: 9 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The film quality of amorphous In–Ga–Zn–O (a-IGZO), an amorphous oxide semiconductor (AOS), was studied by the microwave photoconductivity decay (μ-PCD) method. Also, μ-PCD mappings over a 6 in. wafer were undertaken. It was found that the peak signal of the decay curve had a strong correlation with the a-IGZO transistor performance and hence the film quality. The film annealed under a wet condition showed the highest mobility and had the highest peak signal. The μ-PCD method was found to be a very useful tool to evaluate the film quality and predict the performance of AOS transistors fabricated under different process conditions.
Show PACS
73.61.Jc Amorphous semiconductors; glasses
73.61.Ga II-VI semiconductors
73.50.Pz Photoconduction and photovoltaic effects
73.50.Mx High-frequency effects; plasma effects
73.50.Dn Low-field transport and mobility; piezoresistance
85.30.Tv Field effect devices

Reversible electron pumping and negative differential resistance in two-step barrier diode under strong terahertz ac field

G. Murillo, P. A. Schulz, and J. C. Arce

Appl. Phys. Lett. 98, 102108 (2011); http://dx.doi.org/10.1063/1.3562309 (3 pages) | Cited 1 time

Online Publication Date: 9 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A computational study, employing a Floquet-transfer-matrix approach, of the current in a model two-step barrier diode under intense ac fields in the terahertz range is reported. It is demonstrated that the field pumps a net tunnel current through the structure, which can exhibit a negative differential resistance and whose direction can be controlled by the ac-bias amplitude. These behaviors are seen to originate from the inelastic scattering of incoming electrons by absorption or emission of field quanta from a shape resonance present in the field-free structure.
Show PACS
85.30.Kk Junction diodes
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)
85.30.De Semiconductor-device characterization, design, and modeling
FREE

Effects of tip induced carrier density in local tunnel spectra of graphene

Shyam K. Choudhary and Anjan K. Gupta

Appl. Phys. Lett. 98, 102109 (2011); http://dx.doi.org/10.1063/1.3555344 (3 pages)

Online Publication Date: 9 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on tip induced carrier density changes in local tunnel spectra of single layer graphene (SLG) with backgate using room-temperature scanning tunneling microscopy (STM) and spectroscopy. The SLG samples, prepared by exfoliation method and verified by Raman spectra, show atomically resolved honeycomb lattice. Local tunnel spectra show two minima with the two moving in opposite directions along the bias axis. One minimum shows nearly a square-root dependence, and the other shows a linear dependence on gate voltage. We understand these features as arising from the STM tip induced and bias voltage dependent change in carrier density in SLG.
Show PACS
72.20.Fr Low-field transport and mobility; piezoresistance
73.40.Gk Tunneling

Influence of the substrate temperature on the Curie temperature and charge carrier density of epitaxial Gd-doped EuO films

T. Mairoser, A. Schmehl, A. Melville, T. Heeg, W. Zander, J. Schubert, D. E. Shai, E. J. Monkman, K. M. Shen, T. Z. Regier, D. G. Schlom, and J. Mannhart

Appl. Phys. Lett. 98, 102110 (2011); http://dx.doi.org/10.1063/1.3563708 (3 pages) | Cited 3 times

Online Publication Date: 10 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Rare earth doping is a standard, yet experimentally poorly understood method to increase the Curie temperature (TC) of the ferromagnetic semiconductor EuO. Here, we report on the charge carrier density (n) and the TC of commonly used 4.2 at. % Gd-doped EuO films grown by molecular-beam epitaxy on (110) oriented YAlO3 substrates at various substrate temperatures (Tsub). Increasing Tsub leads to a decrease in n and TC. For high substrate temperatures the Gd-doping is rendered completely inactive: n and TC drop to the values of undoped EuO.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
73.61.Le Other inorganic semiconductors
73.50.Dn Low-field transport and mobility; piezoresistance
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
61.72.up Other materials
75.50.Dd Nonmetallic ferromagnetic materials

Mode-filtered electron injection into a waveguide interferometer

Sven S. Buchholz, Ulrich Kunze, Dirk Reuter, Andreas D. Wieck, and Saskia F. Fischer

Appl. Phys. Lett. 98, 102111 (2011); http://dx.doi.org/10.1063/1.3563714 (3 pages)

Online Publication Date: 10 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Injection of mode-filtered electrons into a phase-sensitive four-terminal waveguide Aharonov–Bohm (AB) ring is studied. An individually tuneable quantum point contact (QPC) in a waveguide lead of the GaAs/AlGaAs-ring allows to selectively couple to one-dimensional modes in the ring. Thus, we demonstrate single-mode transport in a multimode waveguide structure. Coherent mode-filtering by the lowest QPC subband is verified by nonlocal bend resistance and phase-sensitive AB interference measurements.
Show PACS
73.23.-b Electronic transport in mesoscopic systems
81.05.Ea III-V semiconductors

Room temperature electrical injection and detection of spin polarized carriers in silicon using MgO tunnel barrier

Nathan W. Gray and Ashutosh Tiwari

Appl. Phys. Lett. 98, 102112 (2011); http://dx.doi.org/10.1063/1.3564889 (3 pages) | Cited 10 times

Online Publication Date: 10 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We are reporting room-temperature, all electrical injection and detection of spin polarized carriers in silicon using NiFe/MgO tunnel-barrier-contacts. From the magnetic field dependence of the spin accumulation voltage, spin-lifetime, and diffusion-length of the carriers were determined to be 276 ps and 328 nm, respectively. For comparison, similar experiments were also performed using NiFe/Al2O3 tunnel-barrier-contacts. However, in the latter case spin-lifetime and diffusion-length were found to be lower ( ∼ 107 ps, 204 nm) demonstrating the superiority of MgO barrier for spin-injection application. Attaining spin diffusion lengths of >320 nm in Si channels is a ground breaking step and opens tremendous opportunities for integrating spin functionality into post-Moore-era electronic devices.
Show PACS
72.25.Hg Electrical injection of spin polarized carriers
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields

Schottky-barrier lowering in silicon nanowire field-effect transistors prepared by metal-assisted chemical etching

M. Zaremba-Tymieniecki and Z. A. K. Durrani

Appl. Phys. Lett. 98, 102113 (2011); http://dx.doi.org/10.1063/1.3565971 (3 pages) | Cited 1 time

Online Publication Date: 10 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the influence of Schottky barrier lowering in Si nanowire field-effect transistors, using nanowires prepared by metal-assisted chemical etching. The experimental electrical characteristics of a p-channel transistor are modeled using thermionic emission of holes across the reverse-biased source Schottky barrier. This barrier is lowered by the image-force potential, and by the electric field generated by both source-drain and gate voltages. The gate voltage lowers the barrier height directly and in addition, modulates the effect of the source-drain voltage on barrier lowering.
Show PACS
85.30.Tv Field effect devices
back to top
RSS Feeds

Micromagnetic study of switching boundary of a spin torque nanodevice

Yan Zhou, Johan Åkerman, and Jonathan Z. Sun

Appl. Phys. Lett. 98, 102501 (2011); http://dx.doi.org/10.1063/1.3561753 (3 pages) | Cited 3 times

Online Publication Date: 7 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on a numerical study of the micromagnetic switching process of a nanostructured spin torque device. We show that incoherent spin waves can be excited over a wide range of current and field even at zero temperature. These large amplitude, incoherent, and nonzero k spin wave modes are shown to alter the switching phase boundary from that calculated within a macrospin model. The presence of telegraphic transitions between different spin wave modes may also contribute to the so-called back-hopping phenomenon where the switching probability varies nonmonotonically with increasing bias current.
Show PACS
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields

Evidence of hydrogen-mediated ferromagnetic coupling in Mn-doped ZnO

Jun Kue Park, Kyu Won Lee, Hyocheon Kweon, and Cheol Eui Lee

Appl. Phys. Lett. 98, 102502 (2011); http://dx.doi.org/10.1063/1.3561775 (3 pages) | Cited 9 times

Online Publication Date: 7 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Hydrogen shallow donors in undoped and doped ZnO systems have been studied by means of the electron paramagnetic resonance and nuclear magnetic resonance measurements. Experimental evidence is given in this work for coupling of hydrogen shallow donors and Mn ions in Mn-doped ZnO mediating short-range ferromagnetic spin-spin interaction.
Show PACS
71.55.Gs II-VI semiconductors
76.30.Lh Other ions and impurities
76.60.-k Nuclear magnetic resonance and relaxation
75.50.Dd Nonmetallic ferromagnetic materials

Influence of GaAs surface structure on tunneling anisotropic magnetoresistance and magnetocrystalline anisotropy in epitaxial Co50Fe50/n-GaAs junctions

Tetsuya Uemura, Masanobu Harada, Takafumi Akiho, Ken-ichi Matsuda, and Masafumi Yamamoto

Appl. Phys. Lett. 98, 102503 (2011); http://dx.doi.org/10.1063/1.3561759 (3 pages) | Cited 5 times

Online Publication Date: 8 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An epitaxial Co50Fe50 layer was grown on As-terminated or Ga-terminated GaAs, and the influence of the termination species on both uniaxial-type tunneling anisotropic magnetoresistance (TAMR) characteristics and magnetocrystalline anisotropy was investigated. The magnetocrystalline anisotropy induced in the Co50Fe50 thin film was strongly dependent on the termination species of the GaAs surface, while the TAMR characteristics were almost unchanged. These experimental findings suggest that the TAMR effect is due to the anisotropy of electronic structure rather than the structural anisotropy.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.30.Gw Magnetic anisotropy
68.55.A- Nucleation and growth
75.50.Bb Fe and its alloys

Improving the performance of superconducting microwave resonators in magnetic fields

D. Bothner, T. Gaber, M. Kemmler, D. Koelle, and R. Kleiner

Appl. Phys. Lett. 98, 102504 (2011); http://dx.doi.org/10.1063/1.3560480 (3 pages) | Cited 2 times

Online Publication Date: 8 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The operation of superconducting coplanar waveguide cavities, as used for circuit quantum electrodynamics and kinetic inductance detectors, in perpendicular magnetic fields normally leads to a reduction in the device performance due to energy dissipating Abrikosov vortices. We experimentally investigate the vortex induced energy losses in such Nb resonators with different spatial distributions of micropatterned pinning sites (antidots) by transmission spectroscopy measurements at 4.2 K. In comparison to resonators without antidots we find a significant reduction in vortex induced losses, and thus increased quality factors over a broad range of frequencies and applied powers in moderate fields.
Show PACS
84.40.Az Waveguides, transmission lines, striplines
85.25.Am Superconducting device characterization, design, and modeling

Optimization of the refrigerant capacity in multiphase magnetocaloric materials

R. Caballero-Flores, V. Franco, A. Conde, K. E. Knipling, and M. A. Willard

Appl. Phys. Lett. 98, 102505 (2011); http://dx.doi.org/10.1063/1.3560445 (3 pages) | Cited 14 times

Online Publication Date: 9 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The refrigerant capacity (RC) of magnetocaloric materials can be enhanced using multiphase materials or composites, which expand the temperature range over which a significant magnetic entropy change can be obtained. Numerical simulations show that by controlling the parameters of the composite (the fraction of the different phases and their Curie temperatures) improvements of RC of ∼ 83% are possible. The maximum applied field plays a crucial, nonmonotonic, role in the optimization. As a proof of concept, it is shown that the combination of two Fe88−2xCoxNixZr7B4Cu1 alloys produces an enhancement in RC of ∼ 37%, making it ∼ 92% larger than that of Gd5Si2Ge1.9Fe0.1.
Show PACS
75.30.Sg Magnetocaloric effect, magnetic cooling
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.40.Mg Numerical simulation studies

Preparation of ferroelectric field effect transistor based on sustainable strongly correlated (Fe,Zn)3O4 oxide semiconductor and their electrical transport properties

Junichi Takaobushi, Teruo Kanki, Tomoji Kawai, and Hidekazu Tanaka

Appl. Phys. Lett. 98, 102506 (2011); http://dx.doi.org/10.1063/1.3564885 (3 pages) | Cited 2 times

Online Publication Date: 10 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have constructed a field effect transistor structure composed of the sustainable oxide semiconductor (Fe,Zn)3O4 with high Curie temperature and ferroelectric Pb(Zr,Ti)O3. Electric field control of (Fe2.5Zn0.5)O4 channel resistance was achieved in the heterostructures though modulation of their carrier concentration. The results will lead to the significant development of sustainable oxide semiconductor spintronics devices working at room temperature.
Show PACS
85.30.Tv Field effect devices
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields

Spin and orbital magnetic moments of molecular beam epitaxy γ′-Fe4N films on LaAlO3(001) and MgO(001) substrates by x-ray magnetic circular dichroism

K. Ito, G. H. Lee, K. Harada, M. Suzuno, T. Suemasu, Y. Takeda, Y. Saitoh, M. Ye, A. Kimura, and H. Akinaga

Appl. Phys. Lett. 98, 102507 (2011); http://dx.doi.org/10.1063/1.3564887 (3 pages) | Cited 5 times

Online Publication Date: 10 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
10-nm-thick γ′-Fe4N films were grown epitaxially on LaAlO3(001) and MgO(001) substrates by molecular beam epitaxy using solid Fe and a radio-frequency NH3 plasma. The lattice mismatch of these substrates to γ′-Fe4N is 0% and 11%, respectively. Spin and orbital magnetic moments of these γ′-Fe4N epitaxial films were deduced by x-ray magnetic circular dichroism measurements at 300 K. The total magnetic moments are almost the same for the two substrates, that is, 2.44±0.06 μB and 2.47±0.06 μB, respectively. These values are very close to those predicted theoretically, and distinctively larger than that for α-Fe.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.30.Cr Saturation moments and magnetic susceptibilities
78.66.Nk Insulators
78.20.Ls Magneto-optical effects
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.A- Nucleation and growth

Modeling bond dilutions in Josephson junction arrays

Jian-Ping Lv and Qing-Hu Chen

Appl. Phys. Lett. 98, 102508 (2011); http://dx.doi.org/10.1063/1.3564891 (3 pages) | Cited 1 time

Online Publication Date: 10 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using resistivity-shunted-junction dynamics, we model bond dilutions in Josephson junction arrays. The current-voltage characteristics are obtained by large-scale numerical simulations. By dynamic scaling analysis to the finite-temperature phase transition, we provide clear evidence for the existence of non-Kosterlitz–Thouless-type phase transition, as described by Kosterlitz et al. [J. Phys. C 6, 1181 (1973) ; J. Phys. C 7, 1046 (1974)] in a wide range of disorder strengths. Critical temperature and exponents of the phase transitions are estimated, which are further confirmed by the finite-size scaling analysis at the transition temperature.
Show PACS
74.50.+r Tunneling phenomena; Josephson effects
74.62.-c Transition temperature variations, phase diagrams

Deep subnanosecond spin torque switching in magnetic tunnel junctions with combined in-plane and perpendicular polarizers

G. E. Rowlands, T. Rahman, J. A. Katine, J. Langer, A. Lyle, H. Zhao, J. G. Alzate, A. A. Kovalev, Y. Tserkovnyak, Z. M. Zeng, H. W. Jiang, K. Galatsis, Y. M. Huai, P. Khalili Amiri, K. L. Wang, et al.

Appl. Phys. Lett. 98, 102509 (2011); http://dx.doi.org/10.1063/1.3565162 (3 pages) | Cited 14 times

Online Publication Date: 10 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We show that adding a perpendicular polarizer to a conventional spin torque memory element with an in-plane free layer and an in-plane polarizer can significantly increase the write speed and decrease the write energy of the element. We demonstrate the operation of such spin torque memory elements with write energies of 0.4 pJ and write times of 0.12 ns.
Show PACS
75.75.-c Magnetic properties of nanostructures
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Multiferroic response to magnetic field in orthorhombic manganites

M. H. Qin, Y. M. Tao, S. Dong, H. B. Zhao, X. S. Gao, and J.-M. Liu

Appl. Phys. Lett. 98, 102510 (2011); http://dx.doi.org/10.1063/1.3565241 (3 pages) | Cited 4 times

Online Publication Date: 10 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The magnetoelectric coupling in Eu0.55Y0.45MnO3 is studied based on a microscopic spin model which includes the superexchange interaction, the single-ion anisotropy, the Dzyaloshinskii–Moriya interaction, and the cubic anisotropy. Our Monte Carlo simulation reproduces the experimentally observed multiferroic response to magnetic field B. It is demonstrated that the magnetic field can control the multiferroic behaviors by modulating the spin arrangements, leading to various flops of electric polarization. In addition, an interesting state in which both the electric polarizations along the a-axis and c-axis are activated under high B is predicted and discussed.
Show PACS
75.85.+t Magnetoelectric effects, multiferroics
75.30.Et Exchange and superexchange interactions
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.30.Gw Magnetic anisotropy
77.22.Ej Polarization and depolarization

Observation of magnetic domain structures in epitaxial MnAs film on GaAs(001) with temperature hysteresis

JinBae Kim, Hiro Akinaga, and Jongryoul Kim

Appl. Phys. Lett. 98, 102511 (2011); http://dx.doi.org/10.1063/1.3564900 (3 pages) | Cited 2 times

Online Publication Date: 11 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The saturation magnetization of MnAs films epitaxially grown on GaAs(001) substrates exhibited temperature hysteresis in the temperature range of 10–45 °C. We investigated the cause of the temperature hysteresis using temperature- and field-controlled magnetic force microscopy (MFM). The MFM results showed that inside the ferromagnetic α-MnAs stripes of the film at 30 °C, 180° domains were formed during cooling but a single domain state was developed during heating. Despite the cooling procedure, a single domain state was found inside the α-MnAs stripes when a magnetic field of 800 Oe was applied. From these results, the spontaneous magnetization of the α-MnAs phase was ascribed to the temperature hysteresis.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.60.Ch Domain walls and domain structure
75.50.Cc Other ferromagnetic metals and alloys
75.70.Kw Domain structure (including magnetic bubbles and vortices)
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close