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12 Mar 2012

Volume 100, Issue 11, Articles (11xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 100, 111101 (2012); http://dx.doi.org/10.1063/1.3691957 (3 pages)

Christina Alpmann, Michael Esseling, Patrick Rose, and Cornelia Denz
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Nonlinear absorption of Sb-based phase change materials due to the weakening of the resonant bond

Shuang Liu, Jingsong Wei, and Fuxi Gan

Appl. Phys. Lett. 100, 111903 (2012); http://dx.doi.org/10.1063/1.3693156 (5 pages) | Cited 3 times

Online Publication Date: 12 March 2012

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The current study proposes a model based on the weakening of the resonant bond to explore the giant optical nonlinear saturable absorption of Sb-based phase change materials. In order to analyze the weakening of resonant bond effectively, we take the Sb2Te3 as an example. First-principle calculations show that both the Born effective charge and optical dielectric constant of crystalline Sb2Te3 in the 300 K to 500 K temperature range monotonically decrease with the temperature, indicating a weakening of the resonant bond. This weakening induces a decline in the absorption coefficient at a rate of 103 m−1 K−1, which results in a nonlinear saturable absorption coefficient in the order of 10−2 m/W. The nonlinear absorption characteristics of the crystalline Sb, Sb7Te3, and Sb2Te3 thin films at 405 nm laser wavelength are measured via z-scan technique using nanosecond laser pulses to validate the above-proposed model. The experimental results are in good agreement with theoretical prediction.
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78.66.Li Other semiconductors
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
77.22.Ch Permittivity (dielectric function)
79.20.Ds Laser-beam impact phenomena

Elimination of higher-order diffraction using zigzag transmission grating in soft x-ray region

H. P. Zang, C. K. Wang, Y. L. Gao, W. M. Zhou, L. Y. Kuang, L. Wei, W. Fan, W. H. Zhang, Z. Q. Zhao, L. F. Cao, Y. Q. Gu, B. H. Zhang, G. Jiang, X. L. Zhu, C. Q. Xie, et al.

Appl. Phys. Lett. 100, 111904 (2012); http://dx.doi.org/10.1063/1.3693395 (4 pages)

Online Publication Date: 12 March 2012

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We present a realization of the sinusoidal transmission function using a series of zigzag-profiled strips where the transmission takes on the binary values 0 and 1 in a two-dimensional distribution. A zigzag transmission grating of 1000 line/mm has been fabricated and demonstrated on the soft x-ray beam of synchrotron radiation. The axial single-order diffraction indicates that the zigzag transmission grating is adequate for spectroscopic application.
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42.79.Dj Gratings
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors

Refraction-type sonic crystal junction diode

Ahmet Cicek, Olgun Adem Kaya, and Bulent Ulug

Appl. Phys. Lett. 100, 111905 (2012); http://dx.doi.org/10.1063/1.3694020 (4 pages) | Cited 4 times

Online Publication Date: 13 March 2012

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Unidirectional sound transmission across a junction of two square sonic crystals with different orientations and lattice constants is numerically investigated. Re-scaling and rotating the wave vectors through refractions across the air-first sonic crystal interface and the junction, respectively, facilitate coupling into the spatial modes of the second crystal. Unidirectional transmission, demonstrated through finite element method simulations, is accomplished between 10.4 kHz and 12.8 kHz. Transmission values to the right and left are greater than 60% and less than 1.0%, respectively, between 11.0 kHz and 12.4 kHz, resulting in a contrast ratio greater than 0.9.
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43.58.-e Acoustical measurements and instrumentation
43.20.El Reflection, refraction, diffraction of acoustic waves
02.60.-x Numerical approximation and analysis

Role of mechanical loads in inducing in-cycle tensile stress in thermally grown oxide

Rene Diaz, Melan Jansz, Mitra Mossaddad, Seetha Raghavan, John Okasinski, Jonathan Almer, Hugo Pelaez-Perez, and Peter Imbrie

Appl. Phys. Lett. 100, 111906 (2012); http://dx.doi.org/10.1063/1.3692592 (4 pages)

Online Publication Date: 14 March 2012

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Experimental in situ synchrotron x-ray diffraction results tracking the strain behavior of the various layers during a cycle, under thermo-mechanical conditions are presented in this work. The quantitative strain measurements here show that the thermally grown oxide briefly experiences in-plane tensile stress (σ22 = +36.4 MPa) with increased mechanical loading during ramp-up in the thermal cycle. These findings are the first in situ experimental observations of these strains under thermo-mechanical conditions, envisaged to serve as a catalyst for crack initiation. The depth resolved measurements of strain taken during applied thermal and mechanical load in this work are a significant step towards achieving realistic testing conditions.
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81.40.Lm Deformation, plasticity, and creep
81.40.Gh Other heat and thermomechanical treatments
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.mt Cracks
62.20.F- Deformation and plasticity

Unusual rigidity and ideal strength of CrB4 and MnB4

Huiyang Gou, Zhiping Li, Hui Niu, Faming Gao, Jingwu Zhang, Rodney C. Ewing, and Jie Lian

Appl. Phys. Lett. 100, 111907 (2012); http://dx.doi.org/10.1063/1.3692777 (4 pages) | Cited 6 times

Online Publication Date: 15 March 2012

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By means of first-principles calculations, we report superior rigidity, ideal tensile, and shear strength for orthorhombic CrB4 and MnB4. The analysis of microscopic deformation mechanism reveals that the unique rectangular boron units in CrB4 and MnB4 are responsible for the consolidation of the directionality of boron-boron covalent bonds and the exceptional rigidity and ideal strength. The unusual mechanical properties of the orthorhombic tetraborides highlight their potential applications as intrinsically superhard materials. The unique rectangular boron unit also implies a criterion for designing and synthesizing transition metal boride based-materials with ultimate hardness and strength.
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81.40.Jj Elasticity and anelasticity, stress-strain relations
81.40.Lm Deformation, plasticity, and creep
62.20.F- Deformation and plasticity
62.20.de Elastic moduli
61.50.Lt Crystal binding; cohesive energy

Gate metal induced reduction of surface donor states of AlGaN/GaN heterostructure on Si-substrate investigated by electroreflectance spectroscopy

Jong Hoon Shin, Young Je Jo, Kwang-Choong Kim, T. Jang, and Kyu Sang Kim

Appl. Phys. Lett. 100, 111908 (2012); http://dx.doi.org/10.1063/1.3695056 (4 pages) | Cited 2 times

Online Publication Date: 16 March 2012

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The surface donor state of AlGaN/GaN heterostructure on Si-substrate was investigated at the presence of Schottky gate metal (Au,Ni) on the surface by using electroreflectance spectroscopy. The sheet carrier density of two-dimensional electron gas (2DEG) decreased significantly from 1.03×1013cm-2 to 5.74×1012cm-2 for Au and from 1.03×1013cm-2 to 3.68×1012cm-2 for Ni upon the introduction of Schottky gate metal. Through the analysis of the depletion of 2DEG, which is attributed to both Schottky junction and the lowered energy of Schottky barrier height, it was concluded that the diminished sheet carrier density of 2DEG originated from the reduction of surface donor state induced by gate metal.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Ns Metal-nonmetal contacts
78.20.Jq Electro-optical effects
73.30.+y Surface double layers, Schottky barriers, and work functions
73.20.At Surface states, band structure, electron density of states
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Quantitative absorption spectra of quantum wires measured by analysis of attenuated internal emissions

Masahiro Yoshita, Takayuki Okada, Hidefumi Akiyama, Makoto Okano, Toshiyuki Ihara, Loren N. Pfeiffer, and Ken W. West

Appl. Phys. Lett. 100, 112101 (2012); http://dx.doi.org/10.1063/1.3693401 (4 pages) | Cited 1 time

Online Publication Date: 12 March 2012

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An absorption-spectroscopy method that utilizes internal emissions as the source of the probe light was used to measure the absorption spectra of quasi-one-dimensional (q-1D) excitons in T-shaped quantum wires embedded in an optical waveguide. The modal absorption area of the 1D ground-state excitons was estimated to be 0.39 eV cm−1 and was almost independent of temperature in the range 4–150 K. Quantitative evaluation using the absorption spectra revealed that the absorption cross-section per unit length at resonance peak and the spectrally integrated absorption cross-section area per unit length of the 1D ground-state excitons were 1.0 nm and 2.5 × 10−3 eV nm, respectively.
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78.67.Lt Quantum wires
78.40.-q Absorption and reflection spectra: visible and ultraviolet
78.55.-m Photoluminescence, properties and materials
73.22.Lp Collective excitations
71.35.-y Excitons and related phenomena

Physical understanding of cryogenic implant benefits for electrical junction stability

Fareen Adeni Khaja, Benjamin Colombeau, Thirumal Thanigaivelan, Deepak Ramappa, and Todd Henry

Appl. Phys. Lett. 100, 112102 (2012); http://dx.doi.org/10.1063/1.3694275 (4 pages)

Online Publication Date: 13 March 2012

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We investigate the effect of cryogenic temperature implants on electrical junction stability for ultra shallow junction applications for sub-32 nm technology nodes and beyond. A comprehensive study was conducted to gain physical understanding of the impact of cryogenic temperature implants on dopant-defect interactions. Carborane (C2B10H12) molecule, a potential alternative to monomer boron was implanted in carbon preamorphized silicon substrates at cryogenic implant temperatures. Results indicate implants at cryogenic temperatures increase dopant activation with reduced diffusion, resulting in lower sheet resistance for a lower junction depth. Further, this study emphasizes the benefits of co-implants performed at cryogenic temperatures as alternative to traditional preamorphizing implants.
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61.72.up Other materials
61.72.U- Doping and impurity implantation
85.40.Ry Impurity doping, diffusion and ion implantation technology
66.30.Ny Chemical interdiffusion; diffusion barriers
61.80.-x Physical radiation effects, radiation damage

Metal enhanced photoluminescence from Al-capped ZnMgO films: The roles of plasmonic coupling and non-radiative recombination

Yanjie Wang, Haiping He, Yalin Zhang, Luwei Sun, Liang Hu, Kewei Wu, Jingyun Huang, and Zhizhen Ye

Appl. Phys. Lett. 100, 112103 (2012); http://dx.doi.org/10.1063/1.3693396 (4 pages) | Cited 5 times

Online Publication Date: 13 March 2012

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Aluminium (Al) enhanced emission is investigated by temperature-dependent photoluminescence (PL) from ZnMgO films grown by metal-organic chemical vapor deposition. The PL enhancement is sensitive to both the thickness of Al film and the temperature. The enhancement ratio increases from 3.5 to ∼51 when temperature decreases from room temperature to 20 K. Increased surface plasmon (SP) coupling and decreased non-radiative recombination rate with decreasing temperature are suggested to account for the giant enhancement. The coupling between the ZnMgO excitons and the SP resonance is confirmed by time-resolved PL.
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78.55.Et II-VI semiconductors
78.66.Hf II-VI semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
81.05.Dz II-VI semiconductors
68.55.ag Semiconductors

Simulation study of channel mobility and device performance dependence on gate stack in graphene field-effect transistors

Weinan Zhu, Jinyu Zhang, and Zhiping Yu

Appl. Phys. Lett. 100, 112104 (2012); http://dx.doi.org/10.1063/1.3693410 (5 pages) | Cited 1 time

Online Publication Date: 13 March 2012

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The channel mobility and device performance of graphene field-effect transistors (GFETs) were investigated using a theoretical model. Surface polarized phonon scattering and charged impurity Coulomb scattering are two dominant scattering mechanisms in carrier mobility calculation. Mobilities are used to calculate the drain current and transconductance of GFETs. Adding a polymer buffer layer (PBL) with low permittivity between graphene and gate dielectric can effectively improve GFETs performance at the expense of decreasing gate controllability. PBL thickness was optimized to achieve best device transconductance. Experimental results and the model calculations of both channel mobility and device transconductance are in agreement.
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85.30.Tv Field effect devices
85.75.Hh Spin polarized field effect transistors
73.61.Wp Fullerenes and related materials
72.20.Fr Low-field transport and mobility; piezoresistance

High-performance uncooled distributed-feedback quantum cascade laser without lateral regrowth

J. C. Zhang, F. Q. Liu, S. Tan, D. Y. Yao, L. J. Wang, L. Li, J. Q. Liu, and Z. G. Wang

Appl. Phys. Lett. 100, 112105 (2012); http://dx.doi.org/10.1063/1.3693425 (4 pages) | Cited 3 times

Online Publication Date: 13 March 2012

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We demonstrate, uncooled, room-temperature continuous-wave (cw) operation of single-mode distributed-feedback (DFB) quantum cascade lasers (QCLs) emitting around 4.6 μm without lateral regrowth. The effects of cavity length on device performance are studied. A record low threshold electrical power consumption of 2.3 W for the entire laser system with a 1.5-mm-long cavity is realized. For the 2-mm-long laser, high cw output power of 125 mW and very low threshold current density of 0.86 kA/cm2 are obtained. Our devices represent an important step towards using uncooled DFB QCLs in mid-infrared spectral range for practical applications.
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42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Optical investigation of degradation mechanisms in AlGaN/GaN high electron mobility transistors: Generation of non-radiative recombination centers

C. Hodges, N. Killat, S. W. Kaun, M. H. Wong, F. Gao, T. Palacios, U. K. Mishra, J. S. Speck, D. Wolverson, and M. Kuball

Appl. Phys. Lett. 100, 112106 (2012); http://dx.doi.org/10.1063/1.3693427 (4 pages) | Cited 2 times

Online Publication Date: 13 March 2012

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Degradation mechanisms in AlGaN/GaN high electron mobility transistors have been studied under pinch-off conditions. Sites of localized emission of electroluminescence (EL) in the form of hotspots, known to be related to gate leakage currents, are shown to be the result of the generation of non-radiative recombination centers in the AlGaN device layer during device stress. EL from the hotspot site contains both hot-carrier emission from the acceleration of charge carriers in the device channel and defect-related transitions. Gate leakage through the generated centers is the most likely mechanism for the observation of EL hotspots.
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85.30.Tv Field effect devices

Scanning tunneling microscopy reveals LiMnAs is a room temperature anti-ferromagnetic semiconductor

A. P. Wijnheijmer, X. Martí, V. Holý, M. Cukr, V. Novák, T. Jungwirth, and P. M. Koenraad

Appl. Phys. Lett. 100, 112107 (2012); http://dx.doi.org/10.1063/1.3693611 (4 pages)

Online Publication Date: 14 March 2012

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We performed scanning tunneling microscopy and spectroscopy on a LiMnAs(001) thin film epitaxially grown on an InAs(001) substrate by molecular beam epitaxy. While the in situ cleavage exposed only the InAs(110) non-polar planes, the cleavage continued into the LiMnAs thin layer across several facets. We combined both topography and current mappings to confirm that the facets correspond to LiMnAs. By spectroscopy we show that LiMnAs has a band gap. The band gap evidenced in this study, combined with the known Néel temperature well above room temperature, confirms that LiMnAs is a promising candidate for exploring the concepts of high temperature semiconductor spintronics based on antiferromagnets.
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68.35.bg Semiconductors
68.55.ag Semiconductors
75.50.Ee Antiferromagnetics
75.50.Pp Magnetic semiconductors
75.70.Ak Magnetic properties of monolayers and thin films
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Evolution of deep electronic states in ZnO during heat treatment in oxygen- and zinc-rich ambients

V. Quemener, L. Vines, E. V. Monakhov, and B. G. Svensson

Appl. Phys. Lett. 100, 112108 (2012); http://dx.doi.org/10.1063/1.3693612 (4 pages) | Cited 4 times

Online Publication Date: 14 March 2012

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Hydrothermally grown ZnO samples have been annealed in Ar, Zn-rich, and O-rich ambients and investigated by deep level transient spectroscopy (DLTS). The DLTS measurements reveal up to 6 different defect levels in the band gap after different annealing conditions. A clear correlation has been found between the annealing treatment and the formation/suppression of two deep defect levels at ∼0.2 and ∼0.5 eV below the conduction band edge (Ec). As a result, the Ec-0.5eV level is assigned to a Zn-rich defect while the Ec-0.2eV level is due to a O-rich defect, where the latter shows donor behavior as revealed by a distinct Poole-Frenkel effect.
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71.55.Gs II-VI semiconductors
72.20.Ht High-field and nonlinear effects
81.40.Gh Other heat and thermomechanical treatments
71.20.Nr Semiconductor compounds

Electrical characterization of a-InGaZnO thin-film transistors with Cu source/drain electrodes

Jaewook Jeong, Gwang Jun Lee, Joonwoo Kim, and Byeongdae Choi

Appl. Phys. Lett. 100, 112109 (2012); http://dx.doi.org/10.1063/1.3694273 (4 pages) | Cited 2 times

Online Publication Date: 15 March 2012

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We analyzed the effects of Cu source/drain (S/D) electrodes on the performance of a-InGaZnO (a-IGZO) thin-film transistors (TFTs). Owing to the Cu migration, the parasitic resistance was as low as 10 Ω cm with small current transfer length. Based on the transfer characteristics, we found that VDS dependent Cu migration creates donor-like deep and tail states in the sub-bandgap region. The feasibility of Cu S/D electrodes for a-IGZO TFTs using inverter circuits indicates that fabrication of high performance circuits is possible by controlling the Cu electro-migration.
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85.30.Tv Field effect devices
85.40.Ls Metallization, contacts, interconnects; device isolation
84.30.Jc Power electronics; power supply circuits

Effects of molecular beam epitaxy growth conditions on composition and optical properties of InxGa1−xBiyAs1−y

Y. Zhong, P. B. Dongmo, J. P. Petropoulos, and J. M. O. Zide

Appl. Phys. Lett. 100, 112110 (2012); http://dx.doi.org/10.1063/1.3695066 (4 pages) | Cited 4 times

Online Publication Date: 16 March 2012

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We describe the growth conditions of InxGa1−xBiyAs1−y (lattice-mismatched and matched) on InP substrates by molecular beam epitaxy and the resulting properties. Due to their anomalously narrow bandgaps and the presence of bismuth, these materials are promising for optoelectronics and thermoelectrics. Low growth temperature and moderate As/Bi beam equivalent pressure ratios are beneficial for Bi incorporation, in good qualitative agreement with GaBiyAs1−y on GaAs. Up to 6.75% bismuth is incorporated. High resolution x-ray diffraction and reciprocal space mapping show that InxGa1−xBiyAs1−y samples exhibit good crystalline quality and zero relaxation. The band gap is reduced in agreement with theoretical predictions. Lattice-matched samples have been produced with lattice mismatch ≤0.21%.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.ag Semiconductors
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
71.20.Nr Semiconductor compounds

Large magnetothermopower effect in Dirac materials (Sr/Ca)MnBi2

Kefeng Wang, Limin Wang, and C. Petrovic

Appl. Phys. Lett. 100, 112111 (2012); http://dx.doi.org/10.1063/1.3695155 (3 pages) | Cited 1 time

Online Publication Date: 16 March 2012

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We report temperature and magnetic field dependence of the thermal transport properties in single crystals of (Sr/Ca)MnBi2 with linear energy dispersion. In SrMnBi2 thermopower is positive, indicating hole-type carriers and the magnetic field enhances the thermopower significantly. The maximum change of thermopower is about 1600% in 9 T field and at 10 K. A negative thermopower is observed in CaMnBi2 with dominant electron-type carriers, and, in contrast, the magnetic field suppresses the absolute value of thermopower. First-principle band structure shows that the chemical potential is close to the Dirac-cone-like points in linear bands. The magnetic field suppresses the apparent Hall carrier density of CaMnBi2 below 50 K. The large magnetothermopower effect in (Sr/Ca)MnBi2 is attributed to the magnetic field shift of chemical potential.
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72.15.Jf Thermoelectric and thermomagnetic effects
71.15.-m Methods of electronic structure calculations
72.15.Gd Galvanomagnetic and other magnetotransport effects
65.40.G- Other thermodynamical quantities
71.20.Lp Intermetallic compounds

Controlling dopant profiles in hyperdoped silicon by modifying dopant evaporation rates during pulsed laser melting

Daniel Recht, Joseph T. Sullivan, Robert Reedy, Tonio Buonassisi, and Michael J. Aziz

Appl. Phys. Lett. 100, 112112 (2012); http://dx.doi.org/10.1063/1.3695171 (3 pages) | Cited 2 times

Online Publication Date: 16 March 2012

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We describe a method to control the sub-surface dopant profile in “hyperdoped” silicon fabricated by ion implantation and pulsed laser melting. Dipping silicon ion implanted with sulfur into hydrofluoric acid prior to nanosecond pulsed laser melting leads to a tenfold increase in the rate of sulfur evaporation from the surface of the melt. This results in an 80% reduction of the near-surface dopant concentration, effectively embedding the hyperdoped region in a layer up to 180 nm beneath the surface. This method should facilitate the development of blocked impurity band devices.
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61.72.uf Ge and Si
61.80.Jh Ion radiation effects
64.70.dj Melting of specific substances
68.47.Fg Semiconductor surfaces
81.05.Cy Elemental semiconductors

A nitrogen-related deep level defect in ion implanted 4H-SiC pn junctions—A spin dependent recombination study

Thomas Aichinger, Patrick M. Lenahan, Blair R. Tuttle, and Dethard Peters

Appl. Phys. Lett. 100, 112113 (2012); http://dx.doi.org/10.1063/1.3695330 (4 pages) | Cited 1 time

Online Publication Date: 16 March 2012

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Nitrogen implantation creates a high density of recombination centers in SiC which can degrade the performance of ion implanted pn junctions. We use spin dependent recombination (SDR) to identify deep level defects associated with these centers. We find a dominating SDR spectrum with three strong lines of equal intensity. The SDR pattern indicates that the observed center is a defect complex involving nitrogen.
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71.55.Ht Other nonmetals
61.72.up Other materials
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Current-driven domain wall motion in heterostructured ferromagnetic nanowires

Youngman Jang, Mark D. Mascaro, G. S. D. Beach, and C. A. Ross

Appl. Phys. Lett. 100, 112401 (2012); http://dx.doi.org/10.1063/1.3692797 (5 pages) | Cited 1 time

Online Publication Date: 12 March 2012

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Micromagnetic modeling shows that the placement of non-magnetic conductive pads on a ferromagnetic wire affects the current-induced velocity of a domain wall (DW) in the wire and can act as a DW chirality filter. The pads shunt the current, causing a non-uniform spin current distribution inside the ferromagnetic wire and an Oersted field transverse to the wire. This suppresses Walker breakdown allowing higher current densities to be imposed before breakdown occurs. The transverse Oersted field pins the DW under some regimes of current density and pad geometry, selectively allowing transmission of DWs of only one chirality.
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75.60.Ch Domain walls and domain structure

Low-damping spin-wave propagation in a micro-structured Co2Mn0.6Fe0.4Si Heusler waveguide

T. Sebastian, Y. Ohdaira, T. Kubota, P. Pirro, T. Brächer, K. Vogt, A. A. Serga, H. Naganuma, M. Oogane, Y. Ando, and B. Hillebrands

Appl. Phys. Lett. 100, 112402 (2012); http://dx.doi.org/10.1063/1.3693391 (3 pages) | Cited 5 times

Online Publication Date: 13 March 2012

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We report on the investigation of spin-wave propagation in a micro-structured Co2Mn0.6Fe0.4Si (CMFS) Heusler waveguide. The reduced magnetic losses of this compound compared to the commonly used Ni81Fe19 allow for the observation of spin-wave propagation over distances as high as 75 μm via Brillouin light scattering (BLS) microscopy. In the linear regime, a maximum decay length of 16.7 μm of the spin-wave amplitude was found. The coherence length of the observed spin-wave modes was estimated to be at least 16 μm via phase-resolved BLS techniques.
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75.30.Ds Spin waves
78.35.+c Brillouin and Rayleigh scattering; other light scattering
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Conductive and ferromagnetic contributions of H in ZnCoO using H2 hot isostatic pressure

Yong Chan Cho, Seunghun Lee, Ho Hyun Nahm, Su Jae Kim, Chul Hong Park, Su Yeon Lee, Sung-Kyu Kim, Chae Ryong Cho, Hideomi Koinuma, and Se-Young Jeong

Appl. Phys. Lett. 100, 112403 (2012); http://dx.doi.org/10.1063/1.3694040 (4 pages) | Cited 1 time

Online Publication Date: 14 March 2012

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For highly H injected ZnCoO achieved by simultaneous high pressure (1000 bar) and annealing using a hot isostatic pressure (HIP), we report electrical and magnetic properties with first-principles calculation results. The HIP process increased the carrier concentration by ∼ 103 times and restored the conductivity up to that of H injected ZnO. Interestingly, with maintaining high conductivity, the extended HIP processing time significantly enhanced the short-ranged spin orderings of Co-H-Co complexes. Based on the experimental and theoretical results, we proposed the explanation for the relation magnetic characteristics and the behavior of hydrogen triggering spin ordering for spintronic applications.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
62.50.-p High-pressure effects in solids and liquids
75.50.Dd Nonmetallic ferromagnetic materials
72.80.Ey III-V and II-VI semiconductors
72.20.My Galvanomagnetic and other magnetotransport effects

Vortex core magnetization dynamics induced by thermal excitation

Tiago S. Machado, Tatiana G. Rappoport, and Luiz C. Sampaio

Appl. Phys. Lett. 100, 112404 (2012); http://dx.doi.org/10.1063/1.3694757 (3 pages) | Cited 1 time

Online Publication Date: 15 March 2012

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We investigate the effect of temperature on the dynamic properties of magnetic vortices in small disks. Our calculations use a stochastic version of the Landau-Lifshitz-Gilbert equation valid for finite temperatures well below the Curie critical temperature. We show that a finite temperature induces a vortex precession around the center of the disk, even in the absence of other excitation sources. We discuss the origin and implications of the appearance of such dynamics. We also show that a temperature gradient plays a role similar to that of a small constant magnetic field.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
02.50.Fz Stochastic analysis
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)

Giant magnetoresistance in layered manganese pnictide CaMnBi2

J. B. He, D. M. Wang, and G. F. Chen

Appl. Phys. Lett. 100, 112405 (2012); http://dx.doi.org/10.1063/1.3694760 (4 pages) | Cited 1 time

Online Publication Date: 15 March 2012

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We report the physical properties of a layered transition metal pnictide, CaMnBi2, which has a crystal structure similar to that of the superconducting iron pnictides. This compound is a bad metal with a long-range antiferromagnetic order at TN = 270 K. The linear temperature dependence of magnetic susceptibility above TN suggests that strong antiferromagnetic correlations exist in the paramagnetic state. A linear magnetic field dependence of the magnetoresistance implies the existence of the linear energy dispersion, which may result in the giant in-plane magnetoresistance (about 105% in 10 T at 2.5 K for H∥c). The results of de Haas-van Alphen effect are consistent with the presence of Dirac fermions.
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74.25.Ha Magnetic properties including vortex structures and related phenomena
74.25.Jb Electronic structure (photoemission, etc.)
75.50.Ee Antiferromagnetics
75.30.Cr Saturation moments and magnetic susceptibilities
75.47.De Giant magnetoresistance
61.66.Fn Inorganic compounds

Enhancement of the Jahn-Teller distortion by magnetization in manganites

Y. Y. Chu, H. H. Wu, S. C. Liu, Hsiu-Hau Lin, J. Matsuno, H. Takagi, J. H. Huang, J. van den Brink, C. T. Chen, and D. J. Huang

Appl. Phys. Lett. 100, 112406 (2012); http://dx.doi.org/10.1063/1.3691946 (3 pages)

Online Publication Date: 15 March 2012

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Show Abstract
Using measurements of resonant x-ray scattering from a LaMnO3/SrMnO3 superlattice grown on SrTiO3(001), we present experimental evidence for the enhancement of the Jahn-Teller distortion by magnetic ordering in manganites. With a specially tuned periodicity of the superlattice, scattering due to the Jahn-Teller (JT) distortion is separated from charge and magnetic scattering. The measured JT distortion is markedly enhanced upon the emergence of magnetization and strongly correlated with the spin ordering in the superlattice. Such strong correlation reveals the nature of electron-electron interaction for orbital ordering in manganites.
Show PACS
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
78.70.Ck X-ray scattering
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
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