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The impact of inter-valley scattering in modifying the density of optically injected spin polarized electrons in AlxGa1−xAs/GaAs heterostructure is investigated. Polarization resolved photoluminescence excitation measurements are performed for studying the spectral dependence of degree of circular polarization (DCP) of photoluminescence signal emanating from an adjacent quantum well layer. The experimental DCP spectra is found to deviate from the theoretically calculated curve at high excitation energy and the deviation is seen to widen with the Al-content of AlxGa1−xAs barrier layer. In the past, researchers had attributed similar deviations to the Dyakonov–Perel (DP) spin relaxation mechanism which dominates the electrons spin dynamics at high excitation energy. However, we find that the inter-valley scattering along with the DP mechanism decide the shape of optical spin orientation spectra at higher energy. In fact, at higher Al-content, the inter-valley scattering in AlxGa1–xAs layer becomes the most dominant mechanism to govern the steady state electron spin polarization at the band edge. A numerical model is also proposed for estimating the steady state electron spin polarization at zone centre by including the inter-valley scattering, energy relaxation and DP spin relaxation mechanisms. [ABSTRACT FROM AUTHOR]

The fascinating Dirac cone in honeycomb graphene, which underlies many unique electronic properties, has inspired the vast endeavors on pursuing new two-dimensional (2D) Dirac materials. Based on the density functional theory method, a 2D material Zn3Si2 of honeycomb transition-metal silicide with intrinsic Dirac cones has been predicted. The Zn3Si2 monolayer is dynamically and thermodynamically stable under ambient conditions. Importantly, the Zn3Si2 monolayer is a room-temperature 2D Dirac material with a spin–orbit coupling energy gap of 1.2 meV, which has an intrinsic Dirac cone arising from the special hexagonal lattice structure. Hole doping leads to the spin polarization of the electron, which results in a Dirac half-metal feature with single-spin Dirac fermion. This novel stable 2D transition-metal-silicon-framework material holds promises for electronic device applications in spintronics. [ABSTRACT FROM AUTHOR]

Spin-polarized electron transport through the zigzag graphene nanoribbon (ZGNR) is investigated by assuming that it couples with different charomium triiodide (CrI3) geometries, respectively. That is to say that the ZGNR either absorbs the monolayer CrI3 or one CrI3 molecule, or couples laterally with one CrI3 molecule. It is found that the spin polarization in the electron transport process is tightly dependent on the CrI3 geometry and the ZGNR-CrI3 coupling manner. When the CrI3 molecule is absorbed on the surface of the ZGNR, the spin-polarization efficiency is much higher than the other two cases, accompanied by the wide spin-polarization region. This work provides a new kind of scheme for optimizing the spin polarization in graphene-based materials. [ABSTRACT FROM AUTHOR]

Developing accurate self-assembly is the key for constructing functional materials from a bottom-up approach. At present, it is mainly hindered by building blocks and driving modes. We design a new self-assembly method based on the magnetic coupling between spin-polarized electrons. First-principles calculations show that spin-polarized electrons from different endohedral metallofullerene (EMF) superatoms can pair each other to ensure a one-dimensional extending morphology. Furthermore, without ligand passivation, the EMF superatoms maintain their electronic structures robustly in self-assembly owing to the core-shell structure and the atomic-like electron arrangement rule. Therefore, it should noted that the magnetic coupling of monomeric electron spin polarization can be an important driving mechanism for high-precision self-assembly. These results represent a new paradigm for self-assembly and offer fresh opportunities for functional material construction at the atomic level. [ABSTRACT FROM AUTHOR]