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

14 Mar 2011

Volume 98, Issue 11, Articles (11xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 98, 111101 (2011); http://dx.doi.org/10.1063/1.3561770 (3 pages)

Mike Woerdemann, Christina Alpmann, and Cornelia Denz
Enlarge Image | Read More
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Observation of continuous and reversible bcc–fcc phase transformation in Ag/V multilayers

Q. M. Wei, X.-Y. Liu, and A. Misra

Appl. Phys. Lett. 98, 111907 (2011); http://dx.doi.org/10.1063/1.3569759 (3 pages) | Cited 2 times

Online Publication Date: 17 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A continuous and reversible bcc–fcc phase transformation via a rotation of bcc{110} or fcc{111} planes is observed in the Bain orientation relationship in a sputter deposited V/Ag multilayers using high resolution transmission electron microscopy and analyzed using molecular dynamics simulations. As a result of the continuous phase transformation, an intermediate bct phase connecting the bcc and fcc phases coexists, giving rise to the Bain path. The periodic displacement of atoms occurs in every two adjacent Ag and V layers. The alternating shear stress created by misfit strain is responsible for generating such transformation.
Show PACS
64.70.kd Metals and alloys
81.15.Cd Deposition by sputtering
68.65.Ac Multilayers
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder

Ab initio molecular dynamics of Al irradiation-induced processes during Al2O3 growth

Denis Music, Farwah Nahif, Kostas Sarakinos, Niklas Friederichsen, and Jochen M. Schneider

Appl. Phys. Lett. 98, 111908 (2011); http://dx.doi.org/10.1063/1.3570650 (3 pages) | Cited 2 times

Online Publication Date: 18 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Al bombardment induced structural changes in α-Al2O3 (R-3c) and γ-Al2O3 (Fd-3m) were studied using ab initio molecular dynamics. Diffusion and irradiation damage occur for both polymorphs in the kinetic energy range from 3.5 to 40 eV. However, for γ-Al2O3(001) subplantation of impinging Al causes significantly larger irradiation damage and hence larger mobility as compared to α-Al2O3. Consequently, fast diffusion along γ-Al2O3(001) gives rise to preferential α-Al2O3(0001) growth, which is consistent with published structure evolution experiments.
Show PACS
61.80.Jh Ion radiation effects
66.30.-h Diffusion in solids
64.70.K- Solid-solid transitions
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
back to top
RSS Feeds

Helicity independent optically-pumped nuclear magnetic resonance in gallium arsenide

Yunpu Li, Jonathan P. King, Le Peng, Maria C. Tamargo, Jeffrey A. Reimer, and Carlos A. Meriles

Appl. Phys. Lett. 98, 112101 (2011); http://dx.doi.org/10.1063/1.3564897 (3 pages)

Online Publication Date: 14 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present new phenomenology for optically-pumped nuclear magnetic resonance (OPNMR) of gallium arsenide. When pumping at low irradiation intensity, the OPNMR signal becomes independent of light helicity. The results are consistent with a mechanism in which the bulk signal represents competition between nuclear quadrupolar and electron-nuclear hyperfine relaxation. This mechanism is further supported by the scaling behavior of OPNMR for isotopes with varying hyperfine and quadrupolar interactions. These results indicate the magnitude and sign of nuclear polarization in the sample may be controlled as a function of depth by tuning photon energy and laser intensity, portending submicron scale patterning of nuclear magnetization.
Show PACS
76.60.Es Relaxation effects
76.60.Gv Quadrupole resonance
71.70.Jp Nuclear states and interactions

Low temperature tunneling current enhancement in silicide/Si Schottky contacts with nanoscale barrier width

Nicolas Reckinger, Xiaohui Tang (唐晓慧), Emmanuel Dubois, Guilhem Larrieu, Denis Flandre, Jean-Pierre Raskin, and Aryan Afzalian

Appl. Phys. Lett. 98, 112102 (2011); http://dx.doi.org/10.1063/1.3567546 (3 pages) | Cited 1 time

Online Publication Date: 16 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The low temperature electrical behavior of adjacent silicide/Si Schottky contacts with or without dopant segregation is investigated. The electrical characteristics are very well modeled by thermionic-field emission for nonsegregated contacts separated by micrometer-sized gaps. Still, an excess of current occurs at low temperature for short contact separations or dopant-segregated contacts when the voltage applied to the device is sufficiently high. From two-dimensional self-consistent nonequilibrium Green’s function simulations, the dependence of the Schottky barrier profile on the applied voltage, unaccounted for in usual thermionic-field emission models, is found to be the source of this deviation.
Show PACS
73.30.+y Surface double layers, Schottky barriers, and work functions
79.70.+q Field emission, ionization, evaporation, and desorption
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

Magnetoresistive switching and highly polarized electroluminescence from semimagnetic semiconductor bicrystals Zn1−xMnxTe

Le Van Khoi and R. R. Gałązka

Appl. Phys. Lett. 98, 112103 (2011); http://dx.doi.org/10.1063/1.3567550 (3 pages)

Online Publication Date: 16 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The Zn1−xMnxTe bicrystals grown by the high-pressure Bridgman method exhibit magnetic-field-sensitive current-voltage characteristics. The threshold voltage of avalanche breakdown decreases by 40% as the magnetic field increases from 0 to 14 T. In the postbreakdown regime, the Zn1−xMnxTe bicrystals emit an intense red and green electroluminescence. Under magnetic field, the green emission exhibits a high degree of circular polarization which reaches 0.95 and 0.78 at 1.8 K and 4.2 K, respectively. The relation between the photon energy of the green emission and the threshold voltage has been studied.
Show PACS
72.20.My Galvanomagnetic and other magnetotransport effects
72.20.Ht High-field and nonlinear effects
75.50.Pp Magnetic semiconductors
81.10.Fq Growth from melts; zone melting and refining
78.60.Fi Electroluminescence

Enhanced photoelectrochemical activity for Cu and Ti doped hematite: The first principles calculations

X. Y. Meng, G. W. Qin, S. Li, X. H. Wen, Y. P. Ren, W. L. Pei, and L. Zuo

Appl. Phys. Lett. 98, 112104 (2011); http://dx.doi.org/10.1063/1.3567766 (3 pages) | Cited 5 times

Online Publication Date: 16 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
To improve photoelectrochemical (PEC) activity of hematite, the modification of energy band by doping 3d transition metal ions Cu and Ti into α-Fe2O3 were studied via the first-principles calculations with density function theory (DFT)+U method. The results show that the band gap of hematite is ∼ 2.1 eV and n-type dopant Ti improves the electric conductivity, confirmed by recent experiments. The p-type dopant Cu enhances the utilization ratio of solar energy, shifts both valance, and conduction band edges to a higher energy level, satisfying hydrogen production in the visible light driven PEC water splitting without voltage bias.
Show PACS
82.50.Hp Processes caused by visible and UV light
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
71.20.Ps Other inorganic compounds
61.72.up Other materials
82.45.-h Electrochemistry and electrophoresis

Impact of Cu/III ratio on the near-surface defects in polycrystalline CuGaSe2 thin films

M. M. Islam, A. Uedono, S. Ishibashi, K. Tenjinbayashi, T. Sakurai, A. Yamada, S. Ishizuka, K. Matsubara, S. Niki, and K. Akimoto

Appl. Phys. Lett. 98, 112105 (2011); http://dx.doi.org/10.1063/1.3567006 (3 pages) | Cited 3 times

Online Publication Date: 17 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Polycrystalline CuGaSe2 thin films grown with various Cu/III( = Cu/Ga) ratios were investigated by positron annihilation spectroscopy (PAS). The line-shape parameter S of the spectra was used to characterize defects in CuGaSe2 films. The S-parameter in positron annihilation spectra increased with decreasing bulk Cu/III ratio in the CuGaSe2 film. Experimental results combined with theoretical calculation show the formation of multiple vacancy-type defect complexes in the near-surface region of the CuGaSe2 film when Cu-content in the film is decreased. These point defects appear to cause the higher S-parameter in PAS measurement.
Show PACS
61.72.jd Vacancies
78.70.Bj Positron annihilation
68.55.ag Semiconductors
71.55.Ht Other nonmetals
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

A spintronic source of circularly polarized single photons

Pablo Asshoff, Andreas Merz, Heinz Kalt, and Michael Hetterich

Appl. Phys. Lett. 98, 112106 (2011); http://dx.doi.org/10.1063/1.3564893 (3 pages) | Cited 2 times

Online Publication Date: 17 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a spintronic single photon source which emits circularly polarized light, where the helicity is determined by an applied magnetic field. Photons are emitted from an InGaAs quantum dot inside an electrically operated spin light-emitting diode, which comprises the diluted magnetic semiconductor ZnMnSe. The circular polarization degree of the emitted light is high, reaching 83% at an applied magnetic field of 2 T and 96% at 6 T. Autocorrelation traces recorded in pulsed operation mode prove the emitted light to be antibunched. The two circular polarization states could be used for representing quantum states |0〉 and |1〉 in quantum cryptography implementations.
Show PACS
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
78.67.Hc Quantum dots
72.25.Dc Spin polarized transport in semiconductors
75.50.Pp Magnetic semiconductors

Low resistance Ti/Au contacts to amorphous gallium indium zinc oxides

Hyunsoo Kim, Kyoung-Kook Kim, Sung-Nam Lee, Jae-Hyun Ryou, and Russell D. Dupuis

Appl. Phys. Lett. 98, 112107 (2011); http://dx.doi.org/10.1063/1.3567796 (3 pages) | Cited 5 times

Online Publication Date: 17 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on low-resistance Ti (50 nm)/Au (80 nm) contacts to amorphous gallium indium zinc oxides (a-GIZO). The specific contact resistances obtained using the transmission line method were as low as 2.85×10−5 Ω cm2 when annealed at 500 °C for 1 min in N2 ambient. This could be attributed to the combined effects of structural relaxation of a-GIZO films at elevated temperatures, causing drastic increases in both electron concentration and Hall mobility, and to interfacial reactions between Ti/Au and a-GIZO layers producing oxygen vacancies near the surface.
Show PACS
73.40.Cg Contact resistance, contact potential
72.20.Ee Mobility edges; hopping transport
81.40.Gh Other heat and thermomechanical treatments

Transport mechanisms in MgO/GaAs(001) delta-doped junctions

S. Le Gall, B. Lépine, G. Delhaye, G. Jézéquel, P. Turban, and P. Schieffer

Appl. Phys. Lett. 98, 112108 (2011); http://dx.doi.org/10.1063/1.3567948 (3 pages)

Online Publication Date: 17 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The transport mechanisms through MgO ultrathin layers (0.5–1.2 nm) deposited on n-type doped GaAs(001) layers have been studied. In order to favor field emission (FE) across the junctions, a high doping concentration layer in vicinity of the semiconductor surfaces has been included. Varying doping concentration of the underlying GaAs layer we find that the dominant transport mechanism is either the variable-range hopping mechanism or a thermionic emission-like process instead of the FE process. The observation of such mechanisms can be explained by the fact that during the MgO deposition, defect states are introduced in the semiconductor band gap.
Show PACS
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
79.40.+z Thermionic emission
72.20.Ee Mobility edges; hopping transport
79.70.+q Field emission, ionization, evaporation, and desorption

Hall resistivity of Fe doped Si film at low temperatures

Y. Q. Xu, W. F. Su, T. X. Nie, J. Cui, Y. M. Shao, and Z. M. Jiang

Appl. Phys. Lett. 98, 112109 (2011); http://dx.doi.org/10.1063/1.3568886 (3 pages)

Online Publication Date: 17 March 2011

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
Nonmonotonically magnetic-field-dependent and sensitively temperature-dependent Hall resistivity of Fe doped Si film has been systematically studied at low temperatures. Two-band of holes conduction mechanism is proposed to be responsible for the observed extraordinary Hall resistivity, as well as magnetoresistance characteristics. Holes in the valence band are generated by thermal activation of electrons from the valence band to shallow acceptor levels with an activation energy of 41.2 meV while holes in acceptor impurity band transport by hopping processes with an activation energy of 2.5 meV. This work shows that even very complicated behavior of Hall resistivity may be understood under a two-band conduction mechanism.
Show PACS
73.61.Cw Elemental semiconductors
73.50.Dn Low-field transport and mobility; piezoresistance
73.50.Lw Thermoelectric effects
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Transport in ferromagnetic GdTiO3/SrTiO3 heterostructures

Pouya Moetakef, Jack Y. Zhang, Alexander Kozhanov, Bharat Jalan, Ram Seshadri, S. James Allen, and Susanne Stemmer

Appl. Phys. Lett. 98, 112110 (2011); http://dx.doi.org/10.1063/1.3568894 (3 pages) | Cited 6 times

Online Publication Date: 17 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Epitaxial GdTiO3/SrTiO3 structures with different SrTiO3 layer thicknesses are grown on (001) (LaAlO3)0.3(Sr2AlTaO6)0.7 substrate surfaces by hybrid molecular beam epitaxy. It is shown that the formation of the pyrochlore (Gd2Ti2O7) phase can be avoided if GdTiO3 is grown by shuttered growth, supplying alternating monolayer doses of Gd and of the metalorganic precursor that supplies both Ti and O. Phase-pure GdTiO3 films grown by this approach exhibit magnetic ordering with a Curie temperature of 30 K. The electrical transport characteristics can be understood as being dominated by a conductive interface layer within the SrTiO3.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.50.Dd Nonmetallic ferromagnetic materials
68.55.A- Nucleation and growth

Electronic transmission selectivity in multiterminal graphitic nanorings

Eduardo C. Girão, Antônio Gomes Souza Filho, and Vincent Meunier

Appl. Phys. Lett. 98, 112111 (2011); http://dx.doi.org/10.1063/1.3563706 (3 pages)

Online Publication Date: 18 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Graphene based toroidal carbon nanostructures possess unique electronic properties induced by quantum confinement and cyclic boundary conditions imposed to the wave-functions along the circumference. We used a tight-binding approach to demonstrate that nanoribbon and nanotube based ring structures have energy-dependent selection rules for electron transmission, especially when they are connected to a large number of terminals.
Show PACS
73.63.Fg Nanotubes
73.22.Pr Electronic structure of graphene
72.20.Ee Mobility edges; hopping transport
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)

Permittivity and microwave absorption of semi-insulating InP at microwave frequencies

Jerzy Krupka, John G. Hartnett, and Mirosław Piersa

Appl. Phys. Lett. 98, 112112 (2011); http://dx.doi.org/10.1063/1.3570689 (3 pages)

Online Publication Date: 18 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Permittivity and dielectric losses of a Fe-doped semi-insulating bulk InP sample were determined at microwave frequencies from 4 to 300 K employing the whispering gallery mode technique. The dielectric loss tangent of the sample at 11 GHz exhibited a local maximum near 12 K. Since the dc conductivity at this temperature was not measurable in our sample the low temperature loss peak is attributed to the local displacement of bound charge carriers.
Show PACS
77.22.Ch Permittivity (dielectric function)
77.22.Gm Dielectric loss and relaxation
84.40.-x Radiowave and microwave (including millimeter wave) technology

Room-temperature nonsaturating magnetoresistance of intrinsic bulk silicon in high pulsed magnetic fields

L. H. Wu, X. Zhang, J. Vanacken, N. Schildermans, C. H. Wan, and V. V. Moshchalkov

Appl. Phys. Lett. 98, 112113 (2011); http://dx.doi.org/10.1063/1.3569139 (3 pages)

Online Publication Date: 18 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nonsaturating positive magnetoresistance (MR) of intrinsic bulk silicon (i-Si) was observed at forward bias, exhibiting an almost linear behavior at high magnetic fields (5 T<B<40 T). The MR reaches 180% at 40 T at room temperature using a bias of 1.5 V, and there is no indication that this MR would saturate at even stronger fields. The nonsaturating large MR of i-Si supports experimentally the hypothesis that the MR of silicon may be induced by inhomogeneous current flows.
Show PACS
72.20.My Galvanomagnetic and other magnetotransport effects
72.80.Cw Elemental semiconductors
back to top
RSS Feeds

Reduction of magnetostatic interactions in self-organized arrays of nickel nanowires using atomic layer deposition

S. Da Col, M. Darques, O. Fruchart, and L. Cagnon

Appl. Phys. Lett. 98, 112501 (2011); http://dx.doi.org/10.1063/1.3562963 (3 pages) | Cited 2 times

Online Publication Date: 14 March 2011

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
Ordered arrays of magnetic nanowires are commonly synthesized by electrodeposition in nanoporous alumina templates. Due to their dense packing, strong magnetostatic interactions prevent the manipulation of wires individually. Using atomic layer deposition we reduce the diameter of the pores prior to electrodeposition. This reduces magnetostatic interactions, yielding fully remanent hysteresis loops. This is a first step toward the use of such arrays for magnetic racetrack memories.
Show PACS
75.75.-c Magnetic properties of nanostructures
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
81.15.Pq Electrodeposition, electroplating
75.50.Tt Fine-particle systems; nanocrystalline materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Resonance modes in arrays of interacting ferromagnetic nanowires subjected to a transverse static magnetic field

Vincent Boucher, Christian Lacroix, Louis-Philippe Carignan, Arthur Yelon, and David Ménard

Appl. Phys. Lett. 98, 112502 (2011); http://dx.doi.org/10.1063/1.3564906 (3 pages) | Cited 1 time

Online Publication Date: 14 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the measurement and modeling of two ferromagnetic resonance (FMR) modes in an array of amorphous CoFeB ferromagnetic nanowires with the applied static magnetic field transverse to the nanowire axes. The two modes are observed below saturation and are excited independently by the components of the microwave magnetic field parallel and perpendicular to the static field. We model the magnetization dynamics of the array as arising from the response of two interacting populations of wires magnetized mirror-symmetrically to each other relative to the plane of the array. The theory is well supported by experimental results obtained from vibrating sample magnetometer and shorted waveguide FMR measurements.
Show PACS
75.75.-c Magnetic properties of nanostructures
75.78.-n Magnetization dynamics
75.30.Cr Saturation moments and magnetic susceptibilities
75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
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

Enhanced Curie temperature in N-deficient GdN

N. O. V. Plank, F. Natali, J. Galipaud, J. H. Richter, M. Simpson, H. J. Trodahl, and B. J. Ruck

Appl. Phys. Lett. 98, 112503 (2011); http://dx.doi.org/10.1063/1.3566996 (3 pages) | Cited 2 times

Online Publication Date: 15 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Polycrystalline GdN thin films have been grown at room temperature with varying N2 pressure. By varying the nitrogen pressure during growth we alter the carrier concentrations of the films. Films grown at low nitrogen pressures display onset of magnetization at temperatures as high as 200 K and a resistivity of 0.3 mΩ cm, whereas films grown at high nitrogen pressures all show a Curie temperature very close to 70 K and resistivity ranges over 1–1000 Ω cm are observed. For all GdN films a peak in the resistivity occurs at TC.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
68.55.A- Nucleation and growth
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
73.61.Ng Insulators
62.50.-p High-pressure effects in solids and liquids

1/f noise in MgO double-barrier magnetic tunnel junctions

G. Q. Yu, Z. Diao, J. F. Feng, H. Kurt, X. F. Han, and J. M. D. Coey

Appl. Phys. Lett. 98, 112504 (2011); http://dx.doi.org/10.1063/1.3562951 (3 pages) | Cited 5 times

Online Publication Date: 16 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Low frequency noise has been investigated in MgO double-barrier magnetic tunnel junctions (DMTJs) with tunneling magnetoresistance (TMR) ratios up to 250% at room temperature. The noise shows a 1/f frequency spectrum and the minimum of the noise magnitude parameter is 1.2×10−10 μm2 in the parallel state for DMTJs annealed at 375 °C. The bias dependence of noise and TMR suggests that DMTJs with MgO barriers can be useful for magnetic field sensor applications.
Show PACS
75.47.Lx Magnetic oxides
72.20.My Galvanomagnetic and other magnetotransport effects
81.40.Gh Other heat and thermomechanical treatments
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
72.70.+m Noise processes and phenomena

Phase-field simulation of strain-induced domain switching in magnetic thin films

Jia-Mian Hu, G. Sheng, J. X. Zhang, C. W. Nan, and L. Q. Chen

Appl. Phys. Lett. 98, 112505 (2011); http://dx.doi.org/10.1063/1.3567542 (3 pages) | Cited 3 times

Online Publication Date: 16 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The strain-induced magnetic domain switching in epitaxial CoFe2O4 (CFO) thin films was studied using phase-field method. In particular, we investigated the domain switching from an initial in-plane direction to out-of-plane under the action of in-plane elastic strains. An abrupt switching feature is observed for a single-domain film while the switching of a multidomain CFO thin film is gradual. Typical magnetic domain structures as a result of the biaxial isotropic in-plane strains are presented.
Show PACS
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.60.Ch Domain walls and domain structure
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity
75.80.+q Magnetomechanical effects, magnetostriction

Magnetic and calorimetric investigations of inverse magnetocaloric effect in Pr0.46Sr0.54MnO3

V. B. Naik, S. K. Barik, R. Mahendiran, and B. Raveau

Appl. Phys. Lett. 98, 112506 (2011); http://dx.doi.org/10.1063/1.3567760 (3 pages) | Cited 8 times

Online Publication Date: 17 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated magnetic entropy change (ΔSm) in the A-type antiferromagnet Pr0.46Sr0.54MnO3 by magnetic and differential scanning calorimetry (DSC) methods. The field-induced antiferromagnetic to ferromagnetic transition is first-order in nature and is accompanied by a large change in the latent heat as evidenced by the DSC data. The ΔSm shows an inverse magnetocaloric effect (ΔSm = +9 J kg−1 K−1 for ΔH = 7 T) around the Neel temperature (TN = 210±2 K) by magnetic measurement, which closely agrees with the calorimetric results. It is suggested that the large positive ΔSm results from a field-induced structural transition that accompanies the destruction of antiferromagnetism.
Show PACS
75.30.Sg Magnetocaloric effect, magnetic cooling
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
65.40.gd Entropy

Switching current reduction using perpendicular anisotropy in CoFeB–MgO magnetic tunnel junctions

P. Khalili Amiri, Z. M. Zeng, J. Langer, H. Zhao, G. Rowlands, Y.-J. Chen, I. N. Krivorotov, J.-P. Wang, H. W. Jiang, J. A. Katine, Y. Huai, K. Galatsis, and K. L. Wang

Appl. Phys. Lett. 98, 112507 (2011); http://dx.doi.org/10.1063/1.3567780 (3 pages) | Cited 9 times

Online Publication Date: 17 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present in-plane CoFeB–MgO magnetic tunnel junctions with perpendicular magnetic anisotropy in the free layer to reduce the spin transfer induced switching current. The tunneling magnetoresistance ratio, resistance-area product, and switching current densities are compared in magnetic tunnel junctions with different CoFeB compositions. The effects of CoFeB free layer thickness on its magnetic anisotropy and current-induced switching characteristics are studied by vibrating sample magnetometry and electrical transport measurements on patterned elliptical nanopillar devices. Switching current densities ∼ 4 MA/cm2 are obtained at 10 ns write times.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.Pq Other materials
75.30.Gw Magnetic anisotropy
back to top
RSS Feeds

Improved magnetoelectric coupling in Mn and Zn doped CoFe2O4–PbZr0.52Ti0.48O3 particulate composite

Arti Gupta, A. Huang, Santiranjan Shannigrahi, and Ratnamala Chatterjee

Appl. Phys. Lett. 98, 112901 (2011); http://dx.doi.org/10.1063/1.3562949 (3 pages) | Cited 1 time

Online Publication Date: 14 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, Mn and Zn simultaneously substituted CoFe2O4, Co0.6Zn0.4Fe1.7Mn0.3O4 has been proposed as magnetostrictive component having the maximum in plane piezomagnetic coupling coefficient (q11+q12 ∼ 0.070 ppm/Oe) at a field of H ∼ 300 Oe with appreciable saturation values of longitudinal and transverse magnetostriction coefficients (λ11 ∼ −20 ppm and λ12 ∼ 10 ppm). On incorporating this in composite (i.e., (x) PbZr0.52Ti0.48O3−(1−x) Co0.6Zn0.4Fe1.7Mn0.3O4) preparation, maximum magnetoelectric voltage coefficients (αE ∼ 122 mV/cm Oe) was obtained in sample x = 0.90 at ac magnetic field of amplitude ∼ 1 Oe and frequency ∼ 1 kHz.
Show PACS
75.80.+q Magnetomechanical effects, magnetostriction
81.20.-n Methods of materials synthesis and materials processing

Al2O3/GeOx/Ge gate stacks with low interface trap density fabricated by electron cyclotron resonance plasma postoxidation

R. Zhang, T. Iwasaki, N. Taoka, M. Takenaka, and S. Takagi

Appl. Phys. Lett. 98, 112902 (2011); http://dx.doi.org/10.1063/1.3564902 (3 pages) | Cited 6 times

Online Publication Date: 16 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An electron cyclotron resonance (ECR) plasma postoxidation method has been employed for forming Al2O3/GeOx/Ge metal-oxide-semiconductor (MOS) structures. X-ray photoelectron spectroscopy and transmission electron microscope characterizations have revealed that a GeOx layer is formed beneath the Al2O3 capping layer by exposing the Al2O3/Ge structures to ECR oxygen plasma. The interface trap density (Dit) of Au/Al2O3/GeOx/Ge MOS capacitors is found to be significantly suppressed down to lower than 1011 cm−2 eV−1. Especially, a plasma postoxidation time of as short as 10 s is sufficient to reduce Dit with maintaining the equivalent oxide thickness (EOT). As a result, the minimum Dit values and EOT of 5×1010 cm−2 eV−1 and 1.67 nm, and 6×1010 cm−2 eV−1 and 1.83 nm have been realized for Al2O3/GeOx/Ge MOS structures with p- and n-type substrates, respectively.
Show PACS
85.30.-z Semiconductor devices
84.32.Tt Capacitors
52.77.-j Plasma applications

Description of the low field nonlinear dielectric properties of ferroelectric and multiferroic materials

C. Borderon, R. Renoud, M. Ragheb, and H. W. Gundel

Appl. Phys. Lett. 98, 112903 (2011); http://dx.doi.org/10.1063/1.3567777 (3 pages)

Online Publication Date: 16 March 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ferroelectric and multiferroic materials present a nonlinear variation in their permittivity due to domain wall motion. Currently, this variation is described either by the Rayleigh law for fields above a threshold or by a power law for soft ferroelectrics. We propose a hyperbolic law based on the contributions of domain walls and intrinsic lattice which includes the two classic approaches. The threshold field is clearly defined by considering reversible and irreversible components of the permittivity. A good agreement between the hyperbolic law and experimental data is obtained. Moreover, we show that the threshold field obeys to the Volgel–Fulcher law.
Show PACS
77.22.Ch Permittivity (dielectric function)
77.80.Dj Domain structure; hysteresis
78.35.+c Brillouin and Rayleigh scattering; other light scattering
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials
75.85.+t Magnetoelectric effects, multiferroics
Page 2 of 4 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close