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Articles 1 - 30 of 163
Full-Text Articles in Engineering
Stabilisation Of Rail Tracks And Underlying Soft Soil Formations, Buddhima Indraratna, Mohamed A. Shahin, Cholachat Rujikiatkamjorn
Stabilisation Of Rail Tracks And Underlying Soft Soil Formations, Buddhima Indraratna, Mohamed A. Shahin, Cholachat Rujikiatkamjorn
Faculty of Engineering - Papers (Archive)
Construction of rail tracks requires appropriate improvement techniques for ballast and underlying soft formation soil, both of which deform and degrade progressively under heavy train loads. This paper aims to demonstrate and discuss some major aspects in relation to stabilisation of ballasted rail tracks overlaying soft formation soils. The use of geocomposites (i.e. bonded geogrid-geotextile layers) for enhancing the performance of rail tracks is described, with the aim of achieving reduced track settlement, increased resilient modulus and decreased ballast degradation. The effects of increasing the confining pressure on rail tracks in regard to particle breakage are studied using laboratory tests. …
Laboratory Measurements Of Dynamic Properties Of Rail Pads Under Incremental Preload, Alexander Remennikov, Sakdirat Kaewunruen
Laboratory Measurements Of Dynamic Properties Of Rail Pads Under Incremental Preload, Alexander Remennikov, Sakdirat Kaewunruen
Faculty of Engineering - Papers (Archive)
Rail pad is an important component in ballasted railway track. Its main function is to attenuate track loads, preventing underneath railway sleepers from excessive stress waves. Generally, the dynamic design of tracks relies on the available data that are mostly focused on the condition at a specific toe load. Recent findings show that track irregularities could significantly amplify the loads on railway tracks. This phenomenon gives rise to a concern that the rail pads may experience higher effective pre-loading than anticipated in the past. On this ground, this paper highlights the significance of accounting for effects of pre-loading on dynamic …
Enhanced Criterion For Base Soil Retention In Embankment Dam Filters, Buddhima Indraratna, A. K. Raut
Enhanced Criterion For Base Soil Retention In Embankment Dam Filters, Buddhima Indraratna, A. K. Raut
Faculty of Engineering - Papers (Archive)
In effective filters, potentially erodible base particles are transported to the filter and retained to form a stable self-filtration layer. At any given time, the mass proportion of the filter and the base materials in this layer depends on the initial porosity of the filter and the subsequent porosity of the self-filtration layer. In this paper, an analytical procedure is given to obtain the particle size distribution (PSD) of the self-filtration layer by combining the PSDs of the filter and the base soil modified by Dc95, where 95% of filter constrictions are finer than the size denoted by Dc95. The …
Behavior Of High Strength Structural Steel At Elevated Temperatures, J. Chen, B. Young, B. Uy
Behavior Of High Strength Structural Steel At Elevated Temperatures, J. Chen, B. Young, B. Uy
Faculty of Engineering - Papers (Archive)
This paper presents the mechanical properties of high strength structural steel and mild structural steel at elevated temperatures. Mechanical properties of structural steel at elevated temperatures are important for fire resistant design of steel structures. However, current design standards for fire resistance of steel structures are mainly based on the investigation of hot-rolled carbon steel with normal strength, such as mild steel. The performance of high strength steel at elevated temperatures is unknown. Hence, an experimental program has been carried out to investigate the mechanical properties of both high strength steel and mild steel at elevated temperatures. The high strength …
Impact Resistance Of Reinforced Concrete Columns: Experimental Studies And Design Considerations, Alexander Remennikov, Sakdirat Kaewunruen
Impact Resistance Of Reinforced Concrete Columns: Experimental Studies And Design Considerations, Alexander Remennikov, Sakdirat Kaewunruen
Faculty of Engineering - Papers (Archive)
There are instances where reinforced concrete structures designed for static loads are subjected to accidental or deliberate impact or blast loads because of industrial or transportation accidents, military or terrorist activities. Analysis and design of structures for such events require realistic assessment of the ulti-mate impact resistance and a mode of failure of the structure. In this paper, a series of falling weight impact tests on conventionally designed reinforced concrete columns are described. The behaviour of quarter-scale reinforced concrete columns under static and impact loads is presented. An impact load was applied at the mid-height of the columns by a …
Non-Destructive Testing (Ndt): A Tool For Dynamic Health Monitoring Of Railway Track Structures, Sakdirat Kaewunruen, Alexander Remennikov
Non-Destructive Testing (Ndt): A Tool For Dynamic Health Monitoring Of Railway Track Structures, Sakdirat Kaewunruen, Alexander Remennikov
Faculty of Engineering - Papers (Archive)
The applications of NDT are varied and recently, an NDT technique known as ‘modal analysis’ was adopted in railway engineering in order to measure track behaviours under either train services or man-made loadings. OVER THE PAST decade, modal testing has become an effective means for identifying, understanding, and simulating dynamic behaviour and responses of structures. One of the techniques widely used in modal analysis is based on an instrumented hammer impact excitation. By using signal analysis, the vibration response of the structures to the impact excitation is measured and transformed into frequency response functions (FRFs) using the Fast Fourier Transformation …
Spherical Clusters Of Nio Nanoshafts For Lithium-Ion Battery Anodes, L. Yuan, Z. P. Guo, Konstantin Konstantinov, P. Munroe, Hua-Kun Liu
Spherical Clusters Of Nio Nanoshafts For Lithium-Ion Battery Anodes, L. Yuan, Z. P. Guo, Konstantin Konstantinov, P. Munroe, Hua-Kun Liu
Faculty of Engineering - Papers (Archive)
Spherical clusters of NiO nanoshafts were prepared using a simple, rapid, and easily scaled up method, i.e., chemical precipitation followed by thermal decomposition. The microstructural characteristics of spherical clusters of nanoshafts were examined by scanning electron microscopy, which showed that the NiO nanoshafts were arranged randomly on the surface of the spherical particles and had grown from the center of the spherical particles to their surface. The electrochemical properties of the assynthesized NiO nanoshaft clusters were investigated to determine their suitability as anode materials for lithium-ion batteries. The nanoshaft cluster electrodes exhibited better reversibility and higher capacities than NiO nanoparticle …
Installation Of A Lime Injection Barrier For The Remediation Of Acid Sulphate Soil Problems, Buddhima Indraratna, A. N. Golab, Laura J. Banasiak
Installation Of A Lime Injection Barrier For The Remediation Of Acid Sulphate Soil Problems, Buddhima Indraratna, A. N. Golab, Laura J. Banasiak
Faculty of Engineering - Papers (Archive)
Oxidation of naturally occurring pyrite (FeS2) in certain low-lying clayey soils generates sulphuric acid, hence the term acid sulphate soils. A horizontal alkaline barrier was installed by radial grouting, for the purpose of remediating leachate from acid sulphate soils and preventing further oxidation. The current research relates to a large-scale field trial of this technique and the effect on the groundwater composition. In coastal Australia, a pyritic layer commonly exists in the soil at shallow depth that is at risk of oxidation, hence the main objective was to inject the barrier above the pyritic layer to (a) stop infiltration of …
Performance And Prediction Of Soft Clay Behavior Under Vacuum Conditions, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Performance And Prediction Of Soft Clay Behavior Under Vacuum Conditions, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Faculty of Engineering - Papers (Archive)
This paper describes the behavior of soft soil foundation under vacuum-assisted preloading at the Second Bangkok International Airport, Thailand. An analytical solution considering the variation of soil permeability and compressibility is proposed. The associated settlement and excess pore pressure at the embankment centerline are predicted and compared with the available field measurement. The field data show that the efficiency of this improvement technique depends on the magnitude and distribution of vacuum pressure as well as on the extent of air leak protection. The height of sand surcharge and consolidation time can be significantly reduced in comparison with the conventional method …
Soft Soil Stabilisation With Special Reference To Road And Railway Embankments, Buddhima Indraratna, Cholachat Rujikiatkamjorn, V. Wijeyakulasuriya, Mohamed A. Shahin, D. Christie
Soft Soil Stabilisation With Special Reference To Road And Railway Embankments, Buddhima Indraratna, Cholachat Rujikiatkamjorn, V. Wijeyakulasuriya, Mohamed A. Shahin, D. Christie
Faculty of Engineering - Papers (Archive)
Much of Australian railway tracks traverse coastal areas containing soft soils and marine deposits. Pre-construction stabilization of soft formation soils by applying a surcharge load alone often takes too long. The installation of prefabricated vertical drains (PVDs) can reduce the preloading period significantly by decreasing the drainage path length, sometimes by a factor of 10 or more. The analytical solution based on actual radial soil permeability is proposed considering the variation of vacuum pressure, and the Cavity Expansion Theory is employed to predict the smear zone caused by the installation of mandrel driven vertical drains. The predicted smear zone and …
Force Analysis And Characterization Of Polymer Actuators, Nam N. Huynh, Gursel Alici, Geoffrey M. Spinks
Force Analysis And Characterization Of Polymer Actuators, Nam N. Huynh, Gursel Alici, Geoffrey M. Spinks
Faculty of Engineering - Papers (Archive)
There has been an increasing interest in conducting polymers, especially polypyrrole (PPy), as potential actuators for many cutting edge applications including micromanipulation and biomedical devices. Their performance needs to be assessed in terms of force and displacement outputs before they can be employed in practical devices. As part of an ongoing project to develop a robotic gripper for micro-manipulation/fabrication applications, this study focuses on (i) deriving a mathematical model to predict the force produced at the tip of a trilayer bending type PPy-based actuator under input voltages, and (ii) experimentally verifying the model. The model has been used to estimate …
Post-Failure Mechanism And Residual Load-Carrying Capacity Of Railway Prestressed Concrete Sleeper Under Hogging Moment, Sakdirat Kaewunruen, Alexander Remennikov
Post-Failure Mechanism And Residual Load-Carrying Capacity Of Railway Prestressed Concrete Sleeper Under Hogging Moment, Sakdirat Kaewunruen, Alexander Remennikov
Faculty of Engineering - Papers (Archive)
Failure mechanisms of engineering structures to various loadings are the key indicators for structural engineers to design and predict the behaviours of such structures. However, the undetermined post-failure mechanisms are of major concern after the structural collapse, due to excessive loading. The residual load-carrying capacity yields the safety allowance to public domain, in order to escape from the incident. In railway practice, the concrete sleepers tend to be subjecting hogging or negative moment at the mid-span, resulting in the negative bending of the sleeper and associated gauge rail rotation. Although the concrete sleeper fails, it still tends to hold the …
Non-Destructive Evaluation For Dynamic Integrity Of Railway Track Structure, Sakdirat Kaewunruen, Alexander Remennikov
Non-Destructive Evaluation For Dynamic Integrity Of Railway Track Structure, Sakdirat Kaewunruen, Alexander Remennikov
Faculty of Engineering - Papers (Archive)
In-field testing for structural integrity using dynamic non-destructive investigation of ballasted railway track structures was carried out and is presented in this paper. A non-destructive technique, ‘modal analysis’, was utilised in this investigation. The railway track structures were dynamically excited using an impact excitation instrumented hammer. Due to the nature of railway track structures that they extrude for a long distance, the transient excitation was given randomly at several local areas. Acceleration responses in time domain were recorded using an accelerometer mounting on the railhead. The frequency response functions (FRFs) can be obtained via the PULSE FFT Analyser. The analytical …
Analytical Modeling And Field Assessment Of Embankment Stabilized With Vertical Drains And Vacuum Preloading, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Iyathurai Sathananthan
Analytical Modeling And Field Assessment Of Embankment Stabilized With Vertical Drains And Vacuum Preloading, Buddhima Indraratna, Cholachat Rujikiatkamjorn, Iyathurai Sathananthan
Faculty of Engineering - Papers (Archive)
This study presents an analytical model of radial drainage with vacuum preloading using compressibility indices and varying horizontal permeability and considers the influence of linearly distributed vacuum pressure along the drain. An analytical solution based on the Cylindrical Cavity Expansion theory is used to evaluate the extent of the smear zone along the drain length and predict the performance of an embankment stabilized with vacuum-assisted prefabricated vertical drains at the New Bangkok International Airport (NBIA). Here, a significantly reduced height of sand surcharge could be applied because excess pore pressure was reduced by vacuum preloading. The performance of the embankment …
Geotechnical Properties Of Ballast And The Role Of Geosynthetics In Rail Track Stabilisation, Buddhima Indraratna, H. Khabbaz, Wadud Salim, D. Christie
Geotechnical Properties Of Ballast And The Role Of Geosynthetics In Rail Track Stabilisation, Buddhima Indraratna, H. Khabbaz, Wadud Salim, D. Christie
Faculty of Engineering - Papers (Archive)
The ballast and its engineering behaviour have a key role in governing the stability and performance of railway tracks. The deformation and degradation behaviour of ballast under static and dynamic loads was studied based on large-scale triaxial testing. The possible use of different types of geosynthetics to improve the performance of fresh and recycled ballast was also investigated. The research findings showed that the inclusion of geosynthetics improves the performance of ballasted tracks.
Thz Emission From Mercury Cadmium Telluride Films Grown On Cadmium Zinc Telluride Substrates, Rajind Mendis, M. L. Smith, R. E. Vickers, R. A. Lewis, C. Zhang
Thz Emission From Mercury Cadmium Telluride Films Grown On Cadmium Zinc Telluride Substrates, Rajind Mendis, M. L. Smith, R. E. Vickers, R. A. Lewis, C. Zhang
Faculty of Engineering - Papers (Archive)
We have observed THz emission from single- and double-layer HgCdTe (MCT) films epitaxially grown on CdZnTe substrates photoexcited by femtosecond laser pulses. The emitted THz radiation was electro-optically detected in reflection-mode at the 45° specular direction. There is a dramatic variation in the emitted signal level from the double-layer samples, whereas the signal level from the single-layer samples shows a relatively constant variation with composition and/or geometry. For the double-layer samples, the highest peak amplitude recorded is 1/5 of that of an InAs emitter, analogous to double that of a standard ZnTe emitter, and shows promise for further enhancement.
Terahertz Absorption In Spintronic Superlattices, C. Zhang, Feng Gao, C. H. Yang
Terahertz Absorption In Spintronic Superlattices, C. Zhang, Feng Gao, C. H. Yang
Faculty of Engineering - Papers (Archive)
In this work we present a theoretical investigation of optical absorption in a spintronic superlattice. It is shown that the Rashba spin-orbit interaction can be used to control the characteristics of the absorption. Our results suggest possible experiments to detect such tunable absorption spectra. The underlying mechanism is the level splitting and linear energy dispersion, both are the consequences of spin-orbit interaction. The proposed absorption properties can be useful in developing spintronic devices in the terahertz regime.
Elastic Visco-Plastic Consolidation Modelling Of Soft Clays Improved By Geosynthetic Vertical Drains, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Elastic Visco-Plastic Consolidation Modelling Of Soft Clays Improved By Geosynthetic Vertical Drains, Cholachat Rujikiatkamjorn, Buddhima Indraratna
Faculty of Engineering - Papers (Archive)
In this paper, an elastic viscoplastic (creep) model is incorporated into the consolidation equation to calculate settlements and excess pore pressures. A finite difference formulation for fully coupled axisymmetric consolidation is adopted to model both vertical and radial consolidation of a multi-layered soil. The effect of smear, non-linear stiffness and varying soil permeability with void ratio can be included in the analysis. The formulation is easily executed in an electronic spreadsheet such as Excel, and it is then validated by existing solutions. Finally, the analysis of a selected case history employing the writers’ formulation is employed to analyse an embankment …
Thz Waveguides: The Evolution, Rajind Mendis
Thz Waveguides: The Evolution, Rajind Mendis
Faculty of Engineering - Papers (Archive)
The development of waveguides is a key element in the technical maturity of the THz field. Suitably designed waveguides can provide innovative solutions for the most fundamental problems of THz energy transfer to the more advanced problems of THz spectroscopy. This presentation will give an overview of the chronological development of THz waveguides, starting from the initial time-domain experiments to the present state-of-the-art, highlighting breakthroughs. Experimental results obtained through waveguide characterization by THz time-domain spectroscopy will be presented and compared to well-known theoretical models, looking at issues related to energy coupling, attenuation, and dispersion, as well as single and multi-mode …
Chandra Observations Of Nuclear Outflows In The Elliptical Galaxy Ngc 4552 In The Virgo Cluster , M. Machacek, P. Nulsen, C. Jones, W. R. Forman
Chandra Observations Of Nuclear Outflows In The Elliptical Galaxy Ngc 4552 In The Virgo Cluster , M. Machacek, P. Nulsen, C. Jones, W. R. Forman
Faculty of Engineering - Papers (Archive)
We use a 54.4 ks Chandra observation to study nuclear outflow activity in NGC 4552 (M89), an elliptical galaxy in the Virgo Cluster. Chandra images in the 0.5–2 keV band show two ringlike features ∼1.7 kpc in diameter in the core of NGC 4552, as reported previously by Filho et al. We use spherically symmetric point explosion shock models to argue that the shape of the surface brightness profile across the rims of the rings and the temperature of hot gas in the rings are consistent with a Mach 1.7 shock carrying mean mechanical power Lshock ∼ 3 × 1041 …
The Starburst In The Abell 1835 Cluster Central Galaxy: A Case Study Of Galaxy Formation Regulated By An Outburst From A Supermassive Black Hole, B. R. Mcnamara, D. A. Rafferty, L. Birzan, J. Steiner, M. W. Wise, P. Nulsen, C. L. Carilli, R. Ryan, M. Sharma
The Starburst In The Abell 1835 Cluster Central Galaxy: A Case Study Of Galaxy Formation Regulated By An Outburst From A Supermassive Black Hole, B. R. Mcnamara, D. A. Rafferty, L. Birzan, J. Steiner, M. W. Wise, P. Nulsen, C. L. Carilli, R. Ryan, M. Sharma
Faculty of Engineering - Papers (Archive)
We present an analysis of the starburst in the Abell 1835 cluster's cD galaxy. The dense gas surrounding the galaxy is radiating X-rays at a rate of ∼1045 ergs s-1, which is consistent with a cooling rate of ∼1000–2000 M⊙ yr-1. However, Chandra and XMM-Newton observations found less than 200 M⊙ yr-1 of cooling below ∼2 keV, a level that is consistent with the cD's current star formation rate of 100–180 M⊙ yr-1. One or more heating agents (feedback) must then be replenishing the remaining radiative losses. Supernova explosions and thermal conduction are unable to do so. However, the active …
Optical Spectrum Of A Two-Dimensional Hole Gas In The Presence Of Spin-Orbit Interaction, C. H. Yang, W. Xu, Z. Zeng, F. Lu, C. Zhang
Optical Spectrum Of A Two-Dimensional Hole Gas In The Presence Of Spin-Orbit Interaction, C. H. Yang, W. Xu, Z. Zeng, F. Lu, C. Zhang
Faculty of Engineering - Papers (Archive)
We present a theoretical study on how the Rashba type of spin splitting affects the optical spectrum of a two-dimensional hole gas (2DHG) realized from a p-type GaAs/AlxGa1−xAs heterojunction. The optical conductivity is evaluated on the basis of the Kubo formula and a standard random-phase approximation for hole-hole interaction in different spin branches. It is found that similar to the case of a spin-split twodimensional electron gas (2DEG), the optical spectrum of a spin-split 2DHG depends strongly on two opticlike plasmon modes caused by collective excitation between two different spin branches. The position and width of the absorption spectrum relate …
Power Generation With Nanowire Resonant Tunneling Thermoelectrics, Mark F. O'Dwyer, H. Linke, E. Hoffmann, T. E. Humphrey, R. A. Lewis, C. Zhang
Power Generation With Nanowire Resonant Tunneling Thermoelectrics, Mark F. O'Dwyer, H. Linke, E. Hoffmann, T. E. Humphrey, R. A. Lewis, C. Zhang
Faculty of Engineering - Papers (Archive)
Nanowires have been predicted to yield significantly improved thermoelectric figures of merit. Here we describe the electron energy spectrum of a resonant tunneling heterostructure nanowire in detail and show how it may be used to realize energy filtering for thermoelectric electronic efficiencies approaching the Carnot limit. A proof-of-principle experiment is described that seeks to demonstrate such idealized electronic properties.
Nonlinear Finite Element Modelling Of Railway Prestressed Concrete Sleeper, Sakdirat Kaewunruen, Alexander Remennikov
Nonlinear Finite Element Modelling Of Railway Prestressed Concrete Sleeper, Sakdirat Kaewunruen, Alexander Remennikov
Faculty of Engineering - Papers (Archive)
Three-dimensional nonlinear finite element model of railway prestressed concrete sleeper has been developed in this study. The general purpose finite element package, ANSYS 10, is employed for the numerical analyses. Using SOLID65 solid element, the compressive crushing of concrete is facilitated using plasticity algorithm while the concrete cracking in tension zone is accommodated by the nonlinear material model. Since the section of concrete sleeper is fully prestressed by nature, the smeared crack analogy is impracticable. Discrete reinforcement modeling with truss elements, LINK8, is then more suitable to utilize. The pre-tensioning is modeled via an initial strain in the tendon elements. …
Rotational Capacity Of Railway Prestressed Concrete Sleeper Under Static Hogging Moment, Sakdirat Kaewunruen, Alexander Remennikov
Rotational Capacity Of Railway Prestressed Concrete Sleeper Under Static Hogging Moment, Sakdirat Kaewunruen, Alexander Remennikov
Faculty of Engineering - Papers (Archive)
Railway prestressed concrete sleeper is an imperative component of ballasted railway tracks. Its main function is to help distribute axle loading to subgrade and formation. By nature, the concrete sleeper is subjected to sagging moment at the railseat zone and to hogging moment at the middle section. Although behaviors of concrete sleepers under static loading have been enormously studied, their rotational characteristic and capacity under such loading have never been reported. The emphases of this paper are placed on the static behavior and rotational capacity of a prestressed concrete sleeper under hogging moment. An Australian manufactured concrete sleeper was used …
Nucleation, Pinning, And Coercivity In Magnetic Nanosystems: An Analytical Micromagnetic Approach , G. P. Zhao, Xiaolin Wang
Nucleation, Pinning, And Coercivity In Magnetic Nanosystems: An Analytical Micromagnetic Approach , G. P. Zhao, Xiaolin Wang
Faculty of Engineering - Papers (Archive)
Nucleation and pinning fields have been derived for an exchange-coupled hard/soft/hard magnetic nanosystem within an analytical micromagnetic approach. For the first time, the analytical formulas can be directly compared with the numerical and experimental coercivity to differentiate the coercivity mechanisms quantitatively. In addition, our analytical results demonstrate that the nucleation field decreases with the soft layer thickness Ls parabolically, rather than reaching a plateau at small Ls as claimed by other reports. The coercivity paradox and the attainable maximum energy product are reexamined based on our results.
Reply To The Discussion By Tran And Mitachi On “Analytical And Numerical Solutions For A Single Vertical Drain Including The Effects Of Vacuum Preloading", Buddhima Indraratna, Cholachat Rujikiatkamjorn, Iyathurai Sathananthan
Reply To The Discussion By Tran And Mitachi On “Analytical And Numerical Solutions For A Single Vertical Drain Including The Effects Of Vacuum Preloading", Buddhima Indraratna, Cholachat Rujikiatkamjorn, Iyathurai Sathananthan
Faculty of Engineering - Papers (Archive)
The writers are grateful for the interest and the feedback provided by the discussers. Responses to their concerns are addressed.
Orientation Dependent Ferroelectric Properties In Samarium Doped Bismuth Titanate Thin Films Grown By The Pulsed-Laser-Ablation Method, Z. Cheng, C. V. Kannan, Kiyoshi Ozawa, H. Kimura, Xiaolin Wang
Orientation Dependent Ferroelectric Properties In Samarium Doped Bismuth Titanate Thin Films Grown By The Pulsed-Laser-Ablation Method, Z. Cheng, C. V. Kannan, Kiyoshi Ozawa, H. Kimura, Xiaolin Wang
Faculty of Engineering - Papers (Archive)
Samarium doped bismuth titanate thin films with the composition of Bi3.25Sm0.75Ti3O12 and with strong preferred orientations along the c axis and the (117) direction were fabricated on Pt/TiO2/SiO2/Si substrate by pulsed laser ablation. Measurements on Pt/BSmT/Pt capacitors showed that the c-axis oriented film had a small remanent polarization (2Pr) of 5 µC/cm2, while the highly (117) oriented film showed a 2Pr value of 54 µC/cm2 at an electrical field of 268 kV/cm and a coercive field Ec of 89 kV/cm. This is different from the sol-gel derived c-axis oriented Bi3.15Sm0.85Ti3O12 film showing a 2Pr value of 49 µC/cm2.
Pressure-Induced Transition In Magnetoresistance Of Single-Walled Carbon Nanotubes, J. Z. Cai, L. Lu, W. J. Kong, H. W. Zhu, C. Zhang, B. Q. Wei, D. H. Wu, F. Liu
Pressure-Induced Transition In Magnetoresistance Of Single-Walled Carbon Nanotubes, J. Z. Cai, L. Lu, W. J. Kong, H. W. Zhu, C. Zhang, B. Q. Wei, D. H. Wu, F. Liu
Faculty of Engineering - Papers (Archive)
We applied hydrostatic pressure (up to 10 GPa) to single-walled carbon nanotube bundles at low temperature (down to 2 K) to measure their magnetoresistance (MR) in a field up to 12 T. We found a pressure-induced transition in MR from positive to negative in the high-field regime. The onset of the transition occurs at 1:5 GPa, which correlates closely with the tube shape transitions. The characteristics of the high-pressure MR are consistent with a model of pressure-induced two-dimensional weak localization.
Constituents Of The Quasiparticle Spectrum Along The Nodal Direction Of High-Tc Cuprates , A. A. Kordyuk, S. V. Borisenko, V. B. Zabolotnyy, J. Geck, M. Knupfer, J. Fink, B. Buchner, C. T. Lin, B. Keimer, H. Berger, A. V. Pan, S. Komiya, Y. Ando
Constituents Of The Quasiparticle Spectrum Along The Nodal Direction Of High-Tc Cuprates , A. A. Kordyuk, S. V. Borisenko, V. B. Zabolotnyy, J. Geck, M. Knupfer, J. Fink, B. Buchner, C. T. Lin, B. Keimer, H. Berger, A. V. Pan, S. Komiya, Y. Ando
Faculty of Engineering - Papers (Archive)
Applying the Kramers-Kronig consistent procedure, developed earlier, we investigate in detail the formation of the quasiparticle spectrum along the nodal direction of high-Tc cuprates. The heavily discussed ‘‘70 meV kink’’ on the renormalized dispersion exhibits a strong temperature and doping dependence when purified from structural effects such as bilayer splitting, diffraction replicas, etc. This dependence is well understood in terms of fermionic and bosonic constituents of the self-energy. The latter follows the evolution of the spin-fluctuation spectrum, emerging below some doping dependent temperature and sharpening below Tc, and is mainly responsible for the formation of the kink in question.