The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
S‐w. Cheong - One of the best experts on this subject based on the ideXlab platform.
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Single‐crystal growth and magnetic properties of La2CuO4 and related compounds (T, T*, and T’ phases) (invited) (abstract)
Journal of Applied Physics, 1991Co-Authors: S‐w. CheongAbstract:We have performed magnetic, transport, and optical measurements on well‐characterized crystals of (un)doped La2CuO4‐related compounds, so‐called T, T* and T’ phases, in order to understand the physical properties of quasi‐2D S=1/2 antiferromagnet with/without added carriers. Single crystals of the (un)doped single‐layer cuprates with large in‐Plane Dimension and optically flat surface have been grown by the flux technique with CuO excess. Ways to control and measure dopant level in the crystals will be discussed. Our various measurements of magnetism in the pristine compounds indicate that magnetic phenomena in the insulating layer systems are qualitatively understandable in terms of classical spin models of 2D S=1/2 antiferromagnet, that is, quantum fluctuation effects, expected to be large in S=1/2 systems, are only perturbative. In this context, we discuss results of various investigations such as studies of magnetic dilution effects, field‐induced transition, two‐magnon scattering, and inelastic neutr...
Francesco Lanza Di Scalea - One of the best experts on this subject based on the ideXlab platform.
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Actuation stress modelling of piezoceramic transducers under variable temperature field
Journal of Intelligent Material Systems and Structures, 2015Co-Authors: Piotr Kijanka, Pawel Packo, Wieslaw J. Staszewski, Francesco Lanza Di ScaleaAbstract:The article presents a two-Dimensional temperature-dependent model of piezoceramic transducers used for Lamb wave–based damage detection applications. The effect of temperature on shear stress and normal stress components influencing wave actuation is analysed. Three models are analysed and compared, that is, static theoretical model and two numerical models, that is, static and dynamic. These models are analysed for two different piezoceramic transducers’ thicknesses. The results demonstrate that the effective transducer’s length is smaller than its physical in-Plane Dimension. The influence of the normal actuation stress component is significant for wave actuation. This component is dependent on temperature and transducer’s Dimension.
Duc-quang Hoang - One of the best experts on this subject based on the ideXlab platform.
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Creation and propagation of a single magnetic domain wall in 2D nanotraps with a square injection pad.
Nanotechnology, 2020Co-Authors: Duc-quang Hoang, Xuan-huu Cao, Hoai Thuong Nguyen, Vinh Ai DaoAbstract:Polycrystalline permalloy 2D nanotraps with a thickness of 20 nm were studied using a Lorentz microscope associated with micro-magnetic simulations. Each trap was designed to create a single head-to-head domain wall. The traps consist of few nanowires with an in-Plane Dimension of w × 1000 nm2(w = 150, 200 and 250 nm). Some structures with an injection pad were also designed to create a single domain wall and propagate it through the structure with the said injection pad. A few of them were patterned to study the nucleation and propagation behaviour of such nucleated domain walls using both horizontal magnetic field and injection pad approaches. The case of a domain wall created at the first corner of the trap with a wire width of 200 nm was systematically studied, whilst single and multiple domain walls can also be created and propagated with or without an injection structure. The characteristics of such movements were exploited with an emphasis on a single head-to-head domain wall.
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Exploring characteristics of the corner sections of a domain wall trap nanostructure with the two-field direction method
RSC Advances, 2018Co-Authors: Vu Ho, Minh-tung Tran, Duy-hien Tong, Duc-quang HoangAbstract:A 2D polycrystalline permalloy domain wall trap nanostructure with a thickness of 20 nm was studied. The structure was alternatively designed and patterned using QCAD/L-Edit software and focused-ion beam technique. With this design, a magnetic domain wall can be created and propagated with a sequence of two-field directions in a Lorentz microscopy. The trap consists of two horizontal nanowires and three 90°-tilted ones. Each nanowire has an in-Plane Dimension of 200 × 1000 nm2. The trap corners were curved to allow a created domain wall that easily moves through the structure. A head-to-head domain-wall aims to create using a continuous field, this created wall can be propagated in the trap using a sequence of two-field directions. The designed trap was simulated using the Object Oriented Micro-Magnetic Framework software. Lorentz microscopy and simulation results indicate that the propagation of a domain wall is strongly affected by the precise roughness behavior of the trap elements. Domain wall pinning and transformation of wall chirality are sensitively correlated to the corner sections of the trap structure and field directions at a certain regime. Using the two-field direction method enables us to explore characteristics of the corner sections of the patterned trap nanostructure. This study is vital to fabricate an optimal nano-trap which supports a reproducible domain wall motion. This also suggests a useful method for the domain wall propagation using sequences of two-field directions. This work provides a better understanding of wall creation and propagation in polycrystalline permalloy curved nanowires which are of interest for concepts of nonvolatile data storage devices.
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Field-driven single domain wall motion in ferromagnetic nanowires
RSC Advances, 2018Co-Authors: Minh-tung Tran, Xuan-huu Cao, Vinh Ai Dao, Duc-the Ngo, Duc-quang HoangAbstract:We present a Lorentz microscopy study of polycrystalline permalloy 2D nanostructures with a thickness of 20 nm. Each structure was designed as a single domain wall trap. The trap comprises two horizontal nanowires with an in-Plane Dimension of 200 × 1000 nm2, and three tilted pads with different shapes. These structures allow us to create head-to-head domain walls, and these created walls can propagate in the structures by an external magnetic field. These designed traps were simulated using the micro-magnetic OOMMF simulation software. Those nanostructures were also patterned using electron beam lithography and focussed-ion beam techniques. This aims to determine the geometric parameters required to propagate a single magnetic domain wall in these structures reproducibly. Among the studied structures with one and two field directions, we found that the motion of a domain wall can be reproducibly driven by two alternative field directions in a trap which consists of the two horizontal nanowires and three 90°-tilted ones. We investigated systematically the viability of both single field and sequential switching of two field directions. Lorentz microscopy and micro-magnetic simulation results indicate that the propagation of a domain wall is strongly affected by the precise shape of the corner sections linking the trap elements, and the angles of the horizontal nanowires and tilted pads. Domain wall pinning and transformation of wall chirality are strongly correlated to the trap geometries. Our results are vital to design an optimal trap which supports a reproducible domain wall motion. This might also support a greater understanding of domain wall creation and propagation in magnetic nanowires which are of interest for concepts of high-density and ultrafast nonvolatile data storage devices, including racetrack memory and magnetic logic gates.
Vinh Ai Dao - One of the best experts on this subject based on the ideXlab platform.
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Creation and propagation of a single magnetic domain wall in 2D nanotraps with a square injection pad.
Nanotechnology, 2020Co-Authors: Duc-quang Hoang, Xuan-huu Cao, Hoai Thuong Nguyen, Vinh Ai DaoAbstract:Polycrystalline permalloy 2D nanotraps with a thickness of 20 nm were studied using a Lorentz microscope associated with micro-magnetic simulations. Each trap was designed to create a single head-to-head domain wall. The traps consist of few nanowires with an in-Plane Dimension of w × 1000 nm2(w = 150, 200 and 250 nm). Some structures with an injection pad were also designed to create a single domain wall and propagate it through the structure with the said injection pad. A few of them were patterned to study the nucleation and propagation behaviour of such nucleated domain walls using both horizontal magnetic field and injection pad approaches. The case of a domain wall created at the first corner of the trap with a wire width of 200 nm was systematically studied, whilst single and multiple domain walls can also be created and propagated with or without an injection structure. The characteristics of such movements were exploited with an emphasis on a single head-to-head domain wall.
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Field-driven single domain wall motion in ferromagnetic nanowires
RSC Advances, 2018Co-Authors: Minh-tung Tran, Xuan-huu Cao, Vinh Ai Dao, Duc-the Ngo, Duc-quang HoangAbstract:We present a Lorentz microscopy study of polycrystalline permalloy 2D nanostructures with a thickness of 20 nm. Each structure was designed as a single domain wall trap. The trap comprises two horizontal nanowires with an in-Plane Dimension of 200 × 1000 nm2, and three tilted pads with different shapes. These structures allow us to create head-to-head domain walls, and these created walls can propagate in the structures by an external magnetic field. These designed traps were simulated using the micro-magnetic OOMMF simulation software. Those nanostructures were also patterned using electron beam lithography and focussed-ion beam techniques. This aims to determine the geometric parameters required to propagate a single magnetic domain wall in these structures reproducibly. Among the studied structures with one and two field directions, we found that the motion of a domain wall can be reproducibly driven by two alternative field directions in a trap which consists of the two horizontal nanowires and three 90°-tilted ones. We investigated systematically the viability of both single field and sequential switching of two field directions. Lorentz microscopy and micro-magnetic simulation results indicate that the propagation of a domain wall is strongly affected by the precise shape of the corner sections linking the trap elements, and the angles of the horizontal nanowires and tilted pads. Domain wall pinning and transformation of wall chirality are strongly correlated to the trap geometries. Our results are vital to design an optimal trap which supports a reproducible domain wall motion. This might also support a greater understanding of domain wall creation and propagation in magnetic nanowires which are of interest for concepts of high-density and ultrafast nonvolatile data storage devices, including racetrack memory and magnetic logic gates.
Piotr Kijanka - One of the best experts on this subject based on the ideXlab platform.
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Actuation stress modelling of piezoceramic transducers under variable temperature field
Journal of Intelligent Material Systems and Structures, 2015Co-Authors: Piotr Kijanka, Pawel Packo, Wieslaw J. Staszewski, Francesco Lanza Di ScaleaAbstract:The article presents a two-Dimensional temperature-dependent model of piezoceramic transducers used for Lamb wave–based damage detection applications. The effect of temperature on shear stress and normal stress components influencing wave actuation is analysed. Three models are analysed and compared, that is, static theoretical model and two numerical models, that is, static and dynamic. These models are analysed for two different piezoceramic transducers’ thicknesses. The results demonstrate that the effective transducer’s length is smaller than its physical in-Plane Dimension. The influence of the normal actuation stress component is significant for wave actuation. This component is dependent on temperature and transducer’s Dimension.