다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

This article reviews the basic theoretical aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations. The Dirac electrons can be controlled by application of external electric and magnetic fields, or by altering sample geometry and/or topology. The Dirac electrons behave in unusual ways in tunneling, confinement, and the integer quantum Hall effect. The electronic properties of graphene stacks are discussed and vary with stacking order and number of layers. Edge (surface) states in graphene depend on the edge termination (zigzag or armchair) and affect the physical properties of nanoribbons. Different types of disorder modify the Dirac equation leading to unusual spectroscopic and transport properties. The effects of electron-electron and electron-phonon interactions in single layer and multilayer graphene are also presented.

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The electronic properties of graphene

Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

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Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Two-dimensional materials are attractive for use in next-generation nanoelectronic devices because, compared to one-dimensional materials, it is relatively easy to fabricate complex structures from them. The most widely studied two-dimensional material is graphene, both because of its rich physics and its high mobility. However, pristine graphene does not have a bandgap, a property that is essential for many applications, including transistors. Engineering a graphene bandgap increases fabrication complexity and either reduces mobilities to the level of strained silicon films or requires high voltages. Although single layers of MoS(2) have a large intrinsic bandgap of 1.8 eV (ref. 16), previously reported mobilities in the 0.5-3 cm(2) V(-1) s(-1) range are too low for practical devices. Here, we use a halfnium oxide gate dielectric to demonstrate a room-temperature single-layer MoS(2) mobility of at least 200 cm(2) V(-1) s(-1), similar to that of graphene nanoribbons, and demonstrate transistors with room-temperature current on/off ratios of 1 × 10(8) and ultralow standby power dissipation. Because monolayer MoS(2) has a direct bandgap, it can be used to construct interband tunnel FETs, which offer lower power consumption than classical transistors. Monolayer MoS(2) could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.

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Single-layer MoS2 transistors

There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

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Graphene and Graphene Oxide: Synthesis, Properties, and Applications

$\mathrm{Zr}{\mathrm{Te}}_{5}$ is a layered material that exhibits intricate topological effects. Intensive theoretical and experimental efforts have been devoted to try to understand the physics in this material. In this paper the temperature dependent magnetotransport properties of $\mathrm{Zr}{\mathrm{Te}}_{5}$ thin flakes are investigated. A characteristic temperature ${T}^{*}$ is observed in the temperature dependence of three different types of magnetoresistance simultaneously, which are the saturated Hall anomaly, the chiral anomaly, and the longitudinal magnetoresistance. Furthermore, the value of ${T}^{*}$ decreases monotonically from 200 to 160 K with increasing thickness of the $\mathrm{Zr}{\mathrm{Te}}_{5}$ thin flakes from 42 to 89 nm. Temperature induced topological phase transitions are attributed to the cause of such anomaly in the three types of magnetoresistance at ${T}^{*}$. Our findings provide a multiparameter indicator for the emergence of topological phase transition in $\mathrm{Zr}{\mathrm{Te}}_{5}$ and could be extended to the study of other topological materials. The temperature dependence of the three types of magnetoresistance also sheds light on the role of anomalous Hall effect in the transport properties of $\mathrm{Zr}{\mathrm{Te}}_{5}$.

Crossover behavior in the magnetoresistance of thin flakes of the topological material Zr Te 5

The invention discloses a FeFET (ferroelectric field effect transistor) and a preparation method thereof The FeFET comprises a substrate, a source region, a drain region, a grid region and a grid, wherein low-dimensional semi-conductor nanomaterial conductive channels are located between the source region and the drain region, and a ferroelectric material film is adopted in the grid region An ultrathin insulating buffer layer without charge traps is inserted between a low-dimensional nanomaterial and the ferroelectric material film, carriers in conductive channels are prevented from being injected into the charge traps of a ferroelectric material, and the problem of reverse hysteresis in an LD (low dimensional)-FeFET is completely solved With the adoption of the FeFET and the preparation method, the popularization and application progress of low-dimensional nonvolatile storage devices is greatly accelerated

FeFET (ferroelectric field effect transistor) and preparation method thereof

Gate-controlled magnetic transitions in Fe3GeTe2 with lithium ion conducting glass substrate*

We have studied the breakdown of the integer quantum Hall (QH) effect with fully broken symmetry, in an ultra-high mobility graphene device sandwiched between two single crystal hexagonal boron nitride substrates. The evolution and stabilities of the QH states are studied quantitatively through the nonlinear transport with dc Hall voltage bias. The mechanism of the QH breakdown in graphene and the movement of the Fermi energy with the electrical Hall field are discussed. This is the first study in which the stabilities of fully symmetry broken QH states are probed all together. Our results raise the possibility that the v=6 states might be a better target for the quantum resistance standard.

Nonlinear Transport of Graphene in the Quantum Hall Regime

Spin-orbit coupling (SOC) can provide essential tools to manipulate electron spins in two-dimensional materials like graphene, which is of great interest for both fundamental physics and spintronics application. In this paper, we report the low-field magnetotransport of in situ hydrogenated graphene where hydrogen atoms are attached to the graphene surface in continuous low temperature and vacuum environment. Transition from weak localization to weak antilocalization with increasing hydrogen adatom density is observed, indicating enhancing Bychkov-Rashba-type SOC in a mirror symmetry broken system. From the low-temperature saturation of phase breaking scattering rate, the existence of spin-flip scattering is identified, which corroborates the existence of magnetic moments in hydrogenated graphene.

Jian-Hao Chen

Papers

Crossover behavior in the magnetoresistance of thin flakes of the topological material Zr Te 5

FeFET (ferroelectric field effect transistor) and preparation method thereof

Gate-controlled magnetic transitions in Fe3GeTe2 with lithium ion conducting glass substrate*

Nonlinear Transport of Graphene in the Quantum Hall Regime

Enhancement of spin-orbit coupling and magnetic scattering in hydrogenated graphene