Graphene growth by low-pressure chemical vapor deposition on low cost copper foils shows great promise for large scale applications. It is known that the local crystallography of the foil influences ...the graphene growth rate. Here we find an epitaxial relationship between graphene and copper foil. Interfacial restructuring between graphene and copper drives the formation of （nl0） facets on what is otherwise a mostly Cu（100） surface, and the facets in turn influence the graphene orientations from the onset of growth. Angle resolved photoemission shows that the electronic structure of the graphene is decoupled from the copper indicating a weak interaction between them. Despite this, two preferred orientations of graphene are found, ±8° from the Cu010 direction, creating a non-uniform distribution of graphene grain boundary misorientation angles. Comparison with the model system of graphene growth on single crystal Cu（110） indicates that this orientational alignment is due to mismatch epitaxy. Despite the differences in symmetry the orientation of the graphene is defined by that of the copper. We expect these observations to not only have importance for controlling and understanding the growth process for graphene on copper, but also to have wider implications for the growth of two-dimensional materials on low cost metal substrates.
The gasification process, which increases the number of broken CC bonds and the abundance of particular oxygenated functional groups, is shown to destroy carbon nanotubes (CNTs). The expansion of ...the defect density and dimensions leads to nonlinear consumption of the CNTs with increasing O dose. Some nanotubes are consumed faster than others, most probably due to higher defect densities.
Finding ways to create and control the spin-dependent properties of two-dimensional electron states (2DESs) is a major challenge for the elaboration of novel spin-based devices. Spin–orbit and ...exchange–magnetic interactions (SOI and EMI) are two fundamental mechanisms that enable access to the tunability of spin-dependent properties of carriers. The silicon surface of HoRh2Si2 appears to be a unique model system, where concurrent SOI and EMI can be visualized and controlled by varying the temperature. The beauty and simplicity of this system lie in the 4f moments, which act as a multiple tuning instrument on the 2DESs, as the 4f projections parallel and perpendicular to the surface order at essentially different temperatures. Here we show that the SOI locks the spins of the 2DESs exclusively in the surface plane when the 4f moments are disordered: the Rashba-Bychkov effect. When the temperature is gradually lowered and the system experiences magnetic order, the rising EMI progressively competes with the SOI leading to a fundamental change in the spin-dependent properties of the 2DESs. The spins rotate and reorient toward the out-of-plane Ho 4f moments. Our findings show that the direction of the spins and the spin-splitting of the two-dimensional electrons at the surface can be manipulated in a controlled way by using only one parameter: the temperature.
We explore a number of different electrochemical, wet chemical, and gas phase approaches to study intercalation and oxidation at the buried graphene-Ge interface. While the previous literature ...focused on the passivation of the Ge surface by chemical vapor deposited graphene, we show that particularly via electrochemical intercalation in a 0.25 N solution of anhydrous sodium acetate in glacial acetic acid, this passivation can be overcome to grow GeO2 under graphene. Angle resolved photoemission spectroscopy, Raman spectroscopy, He ion microscopy, and time-of-flight secondary ion mass spectrometry show that the monolayer graphene remains undamaged and its intrinsic strain is released by the interface oxidation. Graphene acts as a protection layer for the as-grown Ge oxide, and we discuss how these insights can be utilized for new processing approaches.
Magnetic Weyl semimetals are a newly discovered class of topological materials that may serve as a platform for exotic phenomena, such as axion insulators or the quantum anomalous Hall effect. Here, ...we use angle-resolved photoelectron spectroscopy and ab initio calculations to discover Weyl cones in CoS2, a ferromagnet with pyrite structure that has been long studied as a candidate for half-metallicity, which makes it an attractive material for spintronic devices. We directly observe the topological Fermi arc surface states that link the Weyl nodes, which will influence the performance of CoS2 as a spin injector by modifying its spin polarization at interfaces. In addition, we directly observe a minority-spin bulk electron pocket in the corner of the Brillouin zone, which proves that CoS2 cannot be a true half-metal.Magnetic Weyl semimetals are a newly discovered class of topological materials that may serve as a platform for exotic phenomena, such as axion insulators or the quantum anomalous Hall effect. Here, we use angle-resolved photoelectron spectroscopy and ab initio calculations to discover Weyl cones in CoS2, a ferromagnet with pyrite structure that has been long studied as a candidate for half-metallicity, which makes it an attractive material for spintronic devices. We directly observe the topological Fermi arc surface states that link the Weyl nodes, which will influence the performance of CoS2 as a spin injector by modifying its spin polarization at interfaces. In addition, we directly observe a minority-spin bulk electron pocket in the corner of the Brillouin zone, which proves that CoS2 cannot be a true half-metal.
In article based on the materials of the American mass media the author constructs the autonomy process of Northeast China during the period preceding the Japanese-Chinese war of 1937-1945. The ...Japanese policy main stages on the creation of the semi-autonomous territories, the reasons interfering this plan implementation in whole, which it should be noted major confrontation in the Japan Cabinet, when the moderate politicians group supporting peaceful resolution of contradictions was headed by the Minister of Foreign Affairs, and the militarists group - the minister of army and the command of Kwantung army supporting him, are established. Concluded that, first, Japan, being afraid of the negative international reaction, tried to solve the problem not military, but diplomatic and methods, and secondly, the Japanese policy on the continent was inconsistent and it was expressed in impossibility at an initial stage to achieve the status of the autonomy for five Chinese provinces and to declare the Autonomous Council of East Hebei, which under control territory covered only small part of one of the Chinese provinces. Creation of the Hopei-Chahar Political Council allowed both the Japanese, and the Chinese sides "to save face", and the military campaign, which began in the summer of 1937, finished the transition process of the China northeast provinces under the Japan control through the creation of the quasi-state the Chinese Republic by the end of 1937. Invaders received in the order such tools as the circulation of the precious metals and drugs, finance, oil monopoly, customs points, etc., thereby having provided complete control over the region economy.
Is graphene on copper doped? Marsden, Alexander J.; Asensio, Maria-Carmen; Avila, José ...
Physica status solidi. PSS-RRL. Rapid research letters,
September 2013, Volume:
7, Issue:
9
Journal Article
PDF
