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Nanoelectronics and Mesoscopic Physics
Published in Vinod Kumar Khanna, Introductory Nanoelectronics, 2020
The GMR effect is qualitatively explained using the Mott model based on the spin state of electrons (Figure 1.7). As we know, the electrons possess an intrinsic angular momentum. The spin quantum number can acquire values ms = ±ℏ/2. In a domain of ferromagnetic material, the spins of the electrons in the atoms are aligned with each other.
Quantization of Maxwell’s Equations and Electromagnetic Field
Published in Maged Marghany, Automatic Detection Algorithms of Oil Spill in Radar Images, 2019
In specific approaches, spin is like a vector quantity; it has a well-defined magnitude, and it has also a direction. Nonetheless, quantization creates a different direction as compared to one of an ordinary vector. In other words, entirely elementary particles of a specified type have the similar magnitude of spin angular momentum, which is designated by allocating the particle a spin quantum number. In fact, a spin quantum number is a quantum number, which parameterizes the inherent angular momentum or simply spin of angular momentum of a specified particle. In other words, it designates the energy, form and coordination of orbitals. In short, each particle has its own Hilbert space, each of which satisfies the usual angular momentum commutation relations and ladder operators defined.
Physics of Semiconductors
Published in Jyoti Prasad Banerjee, Suranjana Banerjee, Physics of Semiconductors and Nanostructures, 2019
Jyoti Prasad Banerjee, Suranjana Banerjee
In an atomic system like hydrogen, the state of an electron is completely specified by four quantum numbers (n, l, ml, and ms), where n is the principal quantum number, l is the orbital quantum number, ml is the magnetic quantum number, and ms is the spin quantum number. The spin quantum number can have two values only, i.e., + 12 and − 12. A particular energy level of the system corresponds to a particular value of n. If a number of independent quantum states corresponding to different values of l, ml, and ms have same value of n or same energy, then these states are degenerate. The degenerate energy level is the energy level that belongs to more than one quantum state. The degeneracy associated with a particular energy level or a particular value of n is 2n2.
Effect of Sr-doping on electronic and thermal properties of Pr2-xSrxFeCrO6 (0≤x≤1) oxide materials synthesized by using sol-gel technique
Published in Journal of Asian Ceramic Societies, 2023
Lav Kush, Sanjay Srivastava, Sanjay Kumar Vajpai, Serguei V. Savilov
The aforementioned XPS discovery also showed that the propensity of spin-orbit splitting in the 2p edges of Cr and Fe may be caused by either the final 2p5 core hole state or by their various oxidation states. While Fe and Cr share a similar valence of + 3 in BO6 and B’O6 octahedra, respectively, these elements can alter their oxidation states by a super interchange of valence between the two octahedra. Because of this, Fe shows up as 2+ and Cr as 4+, and these two can begin their spin-orbit coupling as a result of unpaired cations with various oxidation states. Moreover, the quantity of unpaired electrons in each orbital can affect the values of the L-S coupling as well as the l and s quantum {∑l (l: azimuthal quantum number) and ∑s (s: spin quantum number)} [16]. Such an exciting finding could help to explain the Cr and Fe disorder in the Pr2-xSrxFeCrO6 lattice. Given that Pr and Sr, unlike Cr and Fe, have stable
Predicting quadrupole relaxation enhancement peaks in proton R1-NMRD profiles in solid Bi-aryl compounds from NQR parameters
Published in Molecular Physics, 2018
Christian Gösweiner, Danuta Kruk, Evrim Umut, Elzbieta Masiewicz, Markus Bödenler, Hermann Scharfetter
Details of how to calculate the NQR powder spectrum will be the matter of the following sections, but to understand the calculation procedure, one has to know that a QN can already exhibit excitable spin transitions at zero magnetic field [26]. Depending on its nuclear spin quantum number I, one can observe – in case of half integer spins – transitions k. As is given by the product of the proton's gyromagnetic ratio times, the applied field in qualitatively the same way as the splitting of quadrupole transitions is given by times , the only determinant of the frequency locations of the transition crossings are the pure quadrupole transition frequencies of the QN at zero magnetic field (see Figure 1). These are the result of an electrical interaction between the electric field gradient (EFG) at the nucleus of interest and its quadrupole moment Q being present in the QN containing molecule.
Application of commercially available fluorophores as triplet spin probes in EPR spectroscopy
Published in Molecular Physics, 2019
Kerstin Serrer, Clemens Matt, Monja Sokolov, Sylwia Kacprzak, Erik Schleicher, Stefan Weber
Molecular triplet states also have other very remarkable properties, such as the initial population of their three spin states far away from that at thermal equilibrium. They are generated in a state called electron–spin polarisation [7], that makes them very interesting for application in magnetic resonance [8], as, due to the low transition frequencies compared to those of optical spectroscopies, magnetic resonance is rather insensitive. This non-Boltzmann population of the triplet-state sublevels arises from symmetry-selective intersystem crossing from the corresponding excited singlet state (total spin quantum number S = 0) to the triplet (S = 1). If this peculiarity is combined with intrinsically rather insensitive techniques, high net magnetizations may be achieved, which in turn tremendously boost the sensitivity of detection, both in electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR). Although this concept has not yet been very widely used, a few methods are now well established and exhibit, in combination with molecular triplet states, their potential for specific purposes: For example, by photo-CIDNP effects, initiated by light-generated triplet-state photochemistry, NMR resonances are enhanced [9,10]. Hyperfine couplings of the electron spin to nearby magnetic nuclei are the decisive parameters modulating the signal amplitude and sign in the liquid state. By a proper analysis of the anomalous NMR intensities, the electronic structure, as reflected by the hyperfine pattern of the investigated radical, is characterised. This allows probing paramagnetic intermediate states [11–14] that in many cases escape other means of detection, for example by EPR.