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Tunable Picosecond Magnetization Dynamics in Ferromagnetic Nanostructures
Published in Klaus D. Sattler, 21st Century Nanoscience – A Handbook, 2020
Samiran Choudhury, Sucheta Mondal, Anulekha De, Anjan Barman
In today’s world, the magnetism has traversed a long way with vast applications in a range of multidisciplinary fields in modern and future nanotechnologies with the rapid invention of several unique magnetic materials, synthesized structures, micro- and nanostructures along with the smart materials. These artificial nanostructures have received enormous attention from both the research and development communities for their promising utilization as non-volatile magnetic memory [1,2], magnetic recording heads [3], magnetic storage media [4], magnetic resonance imaging [5] as well as in the field of biology such as nano-biomedicine [6] and health science [7]. More recently, the immense progress in the nanoengineering is proposed in the fields of various spin-based logic systems [8,9], spin-torque (ST) and spin-Hall nano-oscillators (SHNO) [10,11], and magnonic crystals (MCs) [12]. But with these growing demands of inventing improved technology, new material properties are required which is not always possible to achieve from natural material. Instead, artificially structured materials may exhibit desirable material properties. A relevant example is the bit-patterned media (BPM) that utilize the ordered arrays of lithographically patterned two-dimensional (2-D) networks of magnetic bits, and the magnetic switching behaviors of such systems including the switching field distribution have been thoroughly investigated.
Anharmonic Excitations in Graphene and Other 2-D Nanomaterials
Published in Kun Zhou, Carbon Nanomaterials, 2020
Elena A. Korznikova, Sergey V. Dmitriev
Another relevant direction of studies of localized states in reduced-dimension lattices is related to active materials and metamaterials. Such materials are designed artificially, and they can have properties that are not found in nature [75]. A variety of potential applications makes this type of material a popular subject of research in many fields, including nonlinear dynamics and energy localizations. Thus, it was shown in [76] that superconducting metamaterials based on a lattice with nearest-neighbor coupling can support stable dissipative breather complexes generated as a weak balance of input power and intrinsic losses. Another example of localized excitation in a new numerically designed material is reported by Sergeev et al. [77], where a lattice of active particles interacting via Morse potential with variable friction coefficient is considered. The initial distribution of particle density is shown in Figure 2.17a. This type of structure can support several types of localized excitations, including quasi–1-D solitons shown in Figure 2.17b. It should be noted, however, that in this structure only moving solitons exist.
Polymeric Materials and Their Components for Biomedical Applications
Published in Savaş Kaya, Sasikumar Yesudass, Srinivasan Arthanari, Sivakumar Bose, Goncagül Serdaroğlu, Materials Development and Processing for Biomedical Applications, 2022
Polymeric components will be the significant material for the invention of green, sustainable, energy-efficient, high quality, economical parts in the new millennium. Polymers exist naturally in the form of DNA, RNA, proteins and polysaccharides in plants and animals. The words ‘poly’ and ‘mers’ means ‘many’ and ‘units’ respectively, which are taken from Greek. Single molecules linking together 3-dimensionally (3D) through the polymerization process are called polymers. Monomers bonded via different molecular interactions produce polymers with different properties. Artificially produced (man-made) polymers are called synthetic polymers.
Analysis of a Double-sided Metasurface Structure for the Design of Multifunctional and Directional Insensitive Devices
Published in IETE Journal of Research, 2023
P. Chakrabarti, Somak Bhattacharyya
The multifunctionality of electronic devices has been a long-lasting pursuit for the electronic system, especially if the functions are mutually exclusive from one another. To go beyond the capabilities of natural materials, metamaterials are promising due to a couple of reasons. Firstly, they can be artificially optimized to offer novel properties which an artificial material cannot achieve. Secondly, they enable the miniaturization of devices due to their low geometrical profile. The 2D analogue of metamaterial, also known as a metasurface, is preferred for nanophotonic systems due to their low electrical thickness, making them easy to integrate. Most of the metasurface devices are based on single-sided metasurface structures employing a metasurface-dielectric–metal configuration, where the dielectric layer is sandwiched between the top layer with a metallic pattern and a bottom metallic plate. Such single-sided metasurface structures are mostly used as an absorber in stealth technology for reducing the radar cross-sectional area [1,2]. However, the presence of a metallic plate at the bottom completely blocks the entire frequency band. This causes a fatal problem in the wireless communication system, where apart from absorbing a particular band of frequency, another band of frequency needs to be transmitted to communicate with other remote devices. A multifunctional device that offers absorption and transmission in two separate bands of frequencies is referred to as a “rasorber” [3,4]. Many rasorbers in microwave regions have been reported. Most of them have used passive circuit elements such as resistance, inductance, and capacitance for their realization [5,6]. Due to the presence of vias for the realization of inductance, such devices are difficult to realize in practice. Later, a re-configurable rasorber based on the PIN diode has been reported [7], which switches the mode of operation from absorption to transmission by applying a suitable bias voltage across the diode. However, the presence of a PIN diode at the bottom makes only one layer re-configurable. In [8], both layers are made re-configurable by embedding the top layer with a PIN diode and the bottom layer with a varactor diode. However, two main challenges are associated with such designs. Firstly, they are not realizable at high frequencies such as THz, infrared, etc. Moreover, such designs limit the directional efficiency of the device, as they can be used for single-side incidence only since the bottom layer is completely grounded.