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Non-Equilibrium Green's Function based Circuit Models for Coherent Spin Devices
摘要： With recent developments in spintronics, it is now possible to envision 'spin-driven' devices with magnets and interconnects that require a new class of transport models using generalized Fermi functions and currents, each with four components: one for charge and three for spin. The corresponding impedance elements are not pure numbers but 4 × 4 matrices. Starting from the Non-Equilibrium Green's Function (NEGF) formalism in the elastic, phase-coherent transport regime, we develop spin generalized Landauer-Büttiker formulas involving such 4 × 4 conductances, for multi-terminal devices in the presence of Normal-Metal (NM) leads. In addition to usual 'terminal' conductances describing currents at the contacts, we provide 'spin-transfer torque' conductances describing the spin currents absorbed by ferromagnetic (FM) regions inside the conductor, specifying both of these currents in terms of Fermi functions at the terminals. We derive universal sum rules and reciprocity relations that would be obeyed by such matrix conductances. Finally, we apply our formulation to two example Hamiltonians describing the Rashba and the Hanle effect in 2D. Our results allows the use of pure quantum transport models as building blocks in constructing circuit models for complex spintronic and nano-magnetic structures and devices for simulation in SPICE-like simulators.
关键词： Rashba effect,spintronics,Landauer-Büttiker formula,spin-transfer torque,Non-Equilibrium Green's Function,Hanle effect,SPICE simulation
更新于2025-09-23 15:23:52
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valley of (In,Al)As/AlAs quantum dots
摘要： The electron-nuclei hyperfine interaction of electrons in indirect band gap (In,Al)As/AlAs quantum dots with type-I band alignment has been experimentally studied by measuring the polarization degree of the photoluminescence in a transverse magnetic field (Hanle effect) and the polarization recovery in a longitudinal magnetic field. The different symmetries of the X valley electron Bloch amplitudes at the As, In, and Al nuclei strongly affect the hyperfine interaction. The hyperfine constants corresponding to these nuclei have been determined.
关键词： X valley,hyperfine constants,Bloch amplitudes,Hanle effect,polarization recovery,photoluminescence,quantum dots,electron-nuclei hyperfine interaction
更新于2025-09-23 15:21:01
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The Sun as a Guide to Stellar Physics || Spectropolarimetry and Magnetic Structures
摘要： The polarization of light originates from a nonisotropic physical state in the light source or media through which the light propagates and carries information about vectorial physical quantities such as the magnetic ?eld, electric ?eld, particle stream, and radiation ?eld in astronomical bodies. Most interest regarding solar observation is in the polarization of spectral lines because they are directly related to speci?c physical quantities through the mechanism by which the spectral lines are polarized. By this connection, spectropolarimetry opens a window to assessing important physical quantities that govern solar activity.
关键词： Hanle′ effect,Magnetic Structures,Solar observation,Zeeman effect,Spectropolarimetry
更新于2025-09-09 09:28:46