Prospects of spintronics based on 2D materials
01 Sep 2017-Wiley Interdisciplinary Reviews: Computational Molecular Science (John Wiley & Sons, Ltd)-Vol. 7, Iss: 5
TL;DR: This work focuses mainly on materials of truly 2D nature, that is, atomic crystal layers such as graphene, phosphorene, monolayer transition metal dichalcogenides, and others, but also highlight current research foci in heterostructures or interfaces.
Abstract: Spintronics holds the promise for future information technologies. Devices based on manipulation of spin are most likely to replace the current silicon complementary metal-oxide semiconductor devices that are based on manipulation of charge. The challenge is to identify or design materials that can be used to generate, detect, and manipulate spin. Since the successful isolation of graphene and other two-dimensional (2D) materials, there has been a strong focus on spintronics based on 2D materials due to their attractive properties, and much progress has been made, both theoretically and experimentally. Here, we summarize recent developments in spintronics based on 2D materials. We focus mainly on materials of truly 2D nature, that is, atomic crystal layers such as graphene, phosphorene, monolayer transition metal dichalcogenides, and others, but also highlight current research foci in heterostructures or interfaces. In particular, we emphasize roles played by computation based on first-principles methods which has contributed significantly in the designs of spintronic materials and devices. We also highlight challenges and suggest possible directions for further studies. WIREs Comput Mol Sci 2017, 7:e1313. doi: 10.1002/wcms.1313
For further resources related to this article, please visit the WIREs website.
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01 Jan 2016
TL;DR: The electronic transport in mesoscopic systems is universally compatible with any devices to read, and is available in the book collection an online access to it is set as public so you can get it instantly.
Abstract: Thank you very much for reading electronic transport in mesoscopic systems. Maybe you have knowledge that, people have look numerous times for their favorite readings like this electronic transport in mesoscopic systems, but end up in harmful downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they juggled with some harmful bugs inside their computer. electronic transport in mesoscopic systems is available in our book collection an online access to it is set as public so you can get it instantly. Our book servers spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Merely said, the electronic transport in mesoscopic systems is universally compatible with any devices to read.
1,220 citations
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TL;DR: In this article, a systematic magnetic force microscope study indicates that ferromagnetism in graphite is the result of localized spins that arise at grain boundaries, which usually only occurs in materials containing elements that form covalent 3d and 4f bonds.
Abstract: Ferromagnetism usually only occurs in materials containing elements that form covalent 3d and 4f bonds. Its occurrence in pure carbon is therefore surprising, even controversial. A systematic magnetic force microscope study indicates that ferromagnetism in graphite is the result of localized spins that arise at grain boundaries.
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TL;DR: In this paper, Zhou et al. investigated the simulation of vacancy defects in graphene layers and showed that two single vacancies coalesce into a 5-8-5 double vacancy at the temperature of 3000 K, and four single vacancies reconstruct into two collective 555-777 defects at higher temperatures.
Abstract: Diffusion, coalescence, and reconstruction of vacancy defects in graphene layers are investigated by tight-binding molecular dynamics (TBMD) simulations and by first principles total energy calculations. It is observed in the TBMD simulations that two single vacancies coalesce into a 5-8-5 double vacancy at the temperature of 3000 K, and it is further reconstructed into a new defect structure, the 555-777 defect, by the Stone-Wales type transformation at higher temperatures. First principles calculations confirm that the 555-777 defect is energetically much more stable than two separated single vacancies, and the energy of the 555-777 defect is also slightly lower than that of the 5-8-5 double vacancy. In TBMD simulation, it is also found that the four single vacancies reconstruct into two collective 555-777 defects which is the unit for the hexagonal haeckelite structure proposed by Terrones et al. [Phys. Rev. Lett. 84, 1716 (2000)].
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TL;DR: Hollen and Gupta as mentioned in this paper showed that the adsorption of a single hydrogen atom on graphene induces a magnetic moment characterized by a ~20 millielectron volt spin-split state at the Fermi energy.
Abstract: Hydrogen atom makes graphene magnetic Graphene has many extraordinary mechanical and electronic properties, but it's not magnetic. To make it so, the simplest strategy is to modify its electronic structure to create unpaired electrons. Researchers can do that by, for example, removing individual carbon atoms or adsorbing hydrogen onto graphene. This has to be done in a very controlled way because of a peculiarity of the graphene's crystal lattice, which consists of two sublattices. Gonzales-Herrero et al. deposited a single hydrogen atom on top of graphene and used scanning tunneling microscopy to detect magnetism on the sublattice lacking the deposited atom (see the Perspective by Hollen and Gupta). Science, this issue p. 437; see also p. 415 Scanning tunneling microscopy shows that a hydrogen atom deposited on graphene makes the complementary sublattice magnetic. [Also see Perspective by Hollen and Gupta] Isolated hydrogen atoms absorbed on graphene are predicted to induce magnetic moments. Here we demonstrate that the adsorption of a single hydrogen atom on graphene induces a magnetic moment characterized by a ~20–millielectron volt spin-split state at the Fermi energy. Our scanning tunneling microscopy (STM) experiments, complemented by first-principles calculations, show that such a spin-polarized state is essentially localized on the carbon sublattice opposite to the one where the hydrogen atom is chemisorbed. This atomically modulated spin texture, which extends several nanometers away from the hydrogen atom, drives the direct coupling between the magnetic moments at unusually long distances. By using the STM tip to manipulate hydrogen atoms with atomic precision, it is possible to tailor the magnetism of selected graphene regions.
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TL;DR: In this article, a multiband tight-binding model is presented to explain the effects the d orbitals play in the spin-orbit coupling at K. The π−σ coupling is found irrelevant to the value of the intrinsic spinorbit-induced gap.
Abstract: The spin-orbit coupling in graphene induces spectral gaps at the high-symmetry points. The relevant gap at the Γ point is similar to the splitting of the p orbitals in the carbon atom, being roughly 8.5 meV. The splitting at the K point is orders of magnitude smaller. Earlier tight-binding theories indicated the value of this intrinsic gap of 1 μeV, based on the σ−π coupling. All-electron first-principles calculations give much higher values, between 25 and 50 μeV, due to the presence of the orbitals of the d symmetry in the Bloch states at K. A realistic multiband tight-binding model is presented to explain the effects the d orbitals play in the spin-orbit coupling at K. The π−σ coupling is found irrelevant to the value of the intrinsic spin-orbit-induced gap. On the other hand, the extrinsic spin-orbit coupling (of the Bychkov-Rashba type), appearing in the presence of a transverse electric field, is dominated by the π−σ hybridization, in agreement with previous theories. Tight-binding parameters are obtained by fitting to first-principles calculations, which also provide qualitative support for the model when considering the trends in the spin-orbit-induced gap in graphene under strain. Finally, an effective single-orbital next-nearest-neighbor hopping model accounting for the spin-orbit effects is derived.
265 citations
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"Prospects of spintronics based on 2..." refers background in this paper
...Instead of wave function, Hohenberg and Kohn proved that the electronic property of a system is entirely determined by its electron density and its energy is a functional of electron density.(94,95) DFT-based methods work directly on electron density....
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TL;DR: In this article, the ground state of an interacting electron gas in an external potential was investigated and it was proved that there exists a universal functional of the density, called F[n(mathrm{r})], independent of the potential of the electron gas.
Abstract: This paper deals with the ground state of an interacting electron gas in an external potential $v(\mathrm{r})$. It is proved that there exists a universal functional of the density, $F[n(\mathrm{r})]$, independent of $v(\mathrm{r})$, such that the expression $E\ensuremath{\equiv}\ensuremath{\int}v(\mathrm{r})n(\mathrm{r})d\mathrm{r}+F[n(\mathrm{r})]$ has as its minimum value the correct ground-state energy associated with $v(\mathrm{r})$. The functional $F[n(\mathrm{r})]$ is then discussed for two situations: (1) $n(\mathrm{r})={n}_{0}+\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{n}(\mathrm{r})$, $\frac{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{n}}{{n}_{0}}\ensuremath{\ll}1$, and (2) $n(\mathrm{r})=\ensuremath{\phi}(\frac{\mathrm{r}}{{r}_{0}})$ with $\ensuremath{\phi}$ arbitrary and ${r}_{0}\ensuremath{\rightarrow}\ensuremath{\infty}$. In both cases $F$ can be expressed entirely in terms of the correlation energy and linear and higher order electronic polarizabilities of a uniform electron gas. This approach also sheds some light on generalized Thomas-Fermi methods and their limitations. Some new extensions of these methods are presented.
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