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0 Ferromagnetism for Spintronics Application
Published in Ram K. Gupta, Sanjay R. Mishra, Tuan Anh Nguyen, Fundamentals of Low Dimensional Magnets, 2023
Ravi Trivedi, Brahmananda Chakroborty
Spintronics is an arising innovation for assembling electronic gadgets that exploit electron spin and its related magnetic properties, rather than utilizing the electrical charge of an electron, to convey data. Spin electronics is additionally called Spintronics, where the twist of an electron is constrained by an outer magnetic field and energizes the electrons. These captivated electrons are utilized to control the electric flow. The objective of spintronics is to foster a semiconductor that can control the magnetism of an electron. When we add the twist level of opportunity to hardware, it will give huge adaptability and usefulness to future electronic items. Magnetic twist properties of electrons are utilized in numerous applications like magnetic memory and magnetic recording.
First Principles Calculations in Exploring the Magnetism of Oxide-Based DMS
Published in Jiabao Yi, Sean Li, Functional Materials and Electronics, 2018
For the continuous shrink of the chip size and limitations of the current microelectronic technique, spintronics device is proposed to be a good candidate for substituting the established electronic devices. Spin instead of charge is used as the logical unit for devices. For one electron spin, it has two states, spin up and spin down. In ferromagnetic (FM) materials, the spins can be aligned in one direction, and a small magnetic field can manipulate the spin state from up to down. These two states of up and down can be used as the logic “on” and “off” of a semiconductor device. Combined both charge and spin information of electrons, spintronics devices are expected to have broader properties and applications, since the spin devices will have many advantages over conventional semiconductor devices, such as low power, high speed, and flow-a-spin current without dissipation.
Introduction
Published in Paolo Di Sia, Mathematics and Physics for Nanotechnology, 2019
It is important to have short ways for moving the information in relation to the spin. Such transfer may be realised by means of close interactions, such as those among nuclear spins, or using mobile objects as the conduction electrons in the semiconductors. The second approach gives more freedom to manipulate the system, but it is also more susceptible to relaxation caused by the transport. One of the first proposals for using electron spin in quantum computing suggested the confinement of electrons in quantum dots, with spins of trapped electrons serving as qubits. With an electron for each quantum dot, each qubit can be readily identified. Individual electron spins can be easily manipulated by a local pulse magnetic field. The controlled exchange interaction among electrons in neighbouring quantum dots can produce entanglement between electron spins. The electron spins relax faster (nanoseconds or microseconds) than nuclear spins (minutes or hours). In the spirit of converting spin information in transport properties, an approach would seem to inject two electron flows in two coupled quantum dots, with one flow totally polarised. Another interesting property combines the extremely long coherence time of nuclear spins with the great industrial silicon experience for producing a scalable quantum computing. The donor nuclear spins are used as qubits in this scheme and also the donor electrons play an important role. Electrons are used to fix the nuclear resonance frequency for onequbit operations and for transferring information among donor nuclear spins through electronic exchange and hyperfine interaction, crucial for two-qubit operations.
Tuning diamond electronic properties for functional device applications
Published in Functional Diamond, 2022
Anliang Lu, Limin Yang, Chaoqun Dang, Heyi Wang, Yang Zhang, Xiaocui Li, Hongti Zhang, Yang Lu
NV center is composed of a substitutional N atom and an adjacent vacancy, as schematically shown in Figure 9(a) [137]. The spin state of NV center can be initialized or read-out by using suitable laser. The electron spin can be manipulated by external factors (e.g. microwave, magnetic and electric field) at room temperature. These unique properties give diamond great application potentials in quantum information and sensing. As NV center is an ideal solid qubit under room temperature, if NV center can be generated and manipulated, it is possible to build room-temperature quantum computers [138,139]. NV can also serve as an atomic-scale sensor with high sensitivity [140–142]. As we can see in Figure 9(b), in biological field, the nanoscale magnetic imaging of ferritins can be realized in a single cell by using the NV center as the sensor [140]. In future, the doctors may use NV center to diagnose the lesion of our body at early stage.
Synthesis of new silica xerogels based on bi-functional 1,3,4-thiadiazole and 1,2,4-triazole adducts
Published in Journal of Sulfur Chemistry, 2019
Afifa Hafidh, Fathi Touati, Ahmed Hichem Hamzaoui
The direct detection of paramagnetic species consisting of unpaired electrons in complex samples is ensured by Electron Spin Resonance (ESR or EPR). The basic principles of ESR consist on the interaction of electromagnetic radiation with magnetic moments caused by electrons (ESR). The magnetic moment of an unpaired electron arises from its ‘spin’ and when placed within an external magnetic field, the electron spin will align parallel or antiparallel in the direction of the magnetic field, which corresponds to a lower (Ms = –1/2) or an upper (Ms = 1/2) energy state. If electromagnetic radiation corresponding to the energy difference applied to the sample, resonance transition is possible between the lower and the upper energy states [53]. The energy difference (ΔE) between these two states is proportional to the strength of the applied magnetic field (B0) (Equation 2): where h is Planck’s constant, ν is the frequency of the electromagnetic radiation, g is a constant terme factor (g = 2.00 for an unpaired electron), and μB is the Bohr magneton.
Symmetry properties of the electron density and following from it limits on the KS-DFT applications
Published in Molecular Physics, 2018
Though the concept of spin has enabled to explain the nature of chemical bond, electron spins are not involved directly in the formation of the latter. The interactions responsible for chemical bonding have a purely electrostatic nature. If we do not take into account the spin interactions, the total spin S is a good quantum number, and the wave functions should be eigenfunctions of . In the central field (atoms), this approximation is known as the Russell–Saunders, or LS-coupling. The spatial coordinates and spin variables in the total electron wave function can be separated, and the latter can be presented as a product of a spatial wave function Φ and a spin wave function Ω. Namely: the wave function anti-symmetric in respect to the electron permutations (obeying the Pauli principle) and describing the state with the total spin S can be constructed as linear combinations of products of spatial and spin wave functions, symmetrised according to the irreducible representations Γ[λ] of the permutation group [22]