The manipulation of magnetism provides a unique opportunity for the development of data storage and spintronic applications. Until now, electrical control, pressure tuning, stacking structure dependence, and nanoscale engineering have been realized. However, as the dimensions are decreased, the decrease of the ferromagnetism phase transition temperature (T c) is a universal trend in ferromagnets. Here, we make a breakthrough to realize the synthesis of 1 and 2 unit cell (UC) Cr2Te3 and discover a room-temperature ferromagnetism in two-dimensional Cr2Te3. The newly observed T c increases strongly from 160 K in the thick flake (40.3 nm) to 280 K in 6 UC Cr2Te3 (7.1 nm). The magnetization and anomalous Hall effect measurements provided unambiguous evidence for the existence of spontaneous magnetization at room temperature. The theoretical model revealed that the reconstruction of Cr2Te3 could result in anomalous thickness-dependent T c. This dimension tuning method opens up a new avenue for manipulation of ferromagnetism.
cube (HMC), [5] high bandwidth memory (HBM), [6,7] and 3D monolithic integration, [8] have been successively developed and achieved some success, the challenge of latency and energy consumption caused by massive data transmission still remains. Therefore, it is urgently necessary to enhance the information interaction capability by improving the architectural relationship between processing and memory units.The emergence of non-von-Neumann architecture solves the problem of the separation of processing and memory units, and alleviates the impact of bus bandwidth on computing efficiency. As a non-Von Neumann architecture, in-memory computing has been considered to be one of the future mainstream trends of hardware implementation for AI algorithms, [9] such as machine learning and deep learning. In-memory computing, where calculations are carried out in situ within each memory unit, [10] has massive parallelism and distributed computing characteristic through integrating millions of memory devices in a crossbar array (Figure 1), analogous to the neurobiological system. [11] Thus, it can radically subvert the von Neumann architecture and achieve the fusion of data processing and storage, thereby totally eliminating the latency and energy loss associated with data access. For enabling this computational architecture, new material systems and highperformance memory devices are highly pursued.2D layered materials refer to the material family that held together by strong in-plane chemical bonds and relatively weak out-of-plane van der Waals interactions, and have attracted worldwide attention due to their unique structure and physical properties. [12][13][14][15][16][17][18][19][20][21] On the one hand, the atomically thin thickness of 2D layered materials provide a significant advantage in achieving high-density integration and low-power operation of high-performance devices. [22][23][24][25][26][27][28] On the other hand, their dangling-bond-free surface and planar structure make them not only compatible with traditional wafer technology, but also can be stacked on top of each other unrestricted by lattice mismatch. Thus, varieties of available 2D layered materials with different electrical properties, such as graphene, transition metal dichalcogenides (TMDs, including MoS 2 , WSe 2 , MoTe 2 , etc.), black phosphorus (BP) and hexagonal boron nitride (h-BN), could be arbitrarily assembled to create a wide range of artificial van der Waals heterostructures (vdWHs) with wholly new functionalities that unavailable in the individual material. [29][30][31][32][33] For example, stable data storage can be realized with the aid of potential barrier formed in vdWHs. [34][35][36][37][38][39] Additionally, It is predicted that the conventional von Neumann computing architecture cannot meet the demands of future data-intensive computing applications due to the bottleneck between the processing and memory units. To try to solve this problem, in-memory computing technology, where calculations are carried out in situ within each nonv...
Photodetection technology has been systematically studied due to wide practical applications in temperature monitoring, thermal image technology, and light communication systems. To date, photodetectors based on multitudes of 2D materials have been reported because of their excellent performance. On account of their novel physical properties with ultrathin thickness, cost‐effective preparation with mechanical transfer process, natural passivated surface without dangling bonds, various bandgaps corresponding with a wide photoresponse, and so on, new 2D materials emerge to play significant roles in the field of photodetection. In this regard, a great advance has been achieved in terms of preparation and device application, especially in the last decade. However, there are still some challenges to obtain high‐performance photodetectors, such as growing high‐quality 2D materials, achieving higher quantum efficiency, effectively separating the photogenerated electron–hole pairs, and so on. In this review, the recent development of the state‐of‐the‐art photodetection composed of 2D materials is summarized. Moreover, the key parameters and mechanisms in photodetectors are highlighted, and an overview on 2D materials and their heterostructures is provided. Finally, the strategies for improving the performance of photodetectors are also highlighted. The review will provide a guide to further practical applications in photodetection devices.
We present a theory for the acceleration of monoenergetic protons, trapped in a self-organized double layer, by short pulse laser irradiation on a thin foil with the specific thickness suggested by the simulation study of Yan et al (2008 Phys. Rev. Lett. 100 135003). The laser ponderomotive force pushes the electrons forward, leaving the ions behind until the space charge electric field balances the ponderomotive force at a distance . For the optimal target thickness D = > c/ω p , the electron sheath is piled up at the rear surface and the sheath electric field accelerates the protons until they are reflected by the inertial force in the accelerated frame. These protons are therefore trapped by the combined forces of the electrostatic field of the electron sheath and the inertial force of the accelerating target. Together with the electron layer, they form a double layer and are collectively accelerated by the laser ponderomotive force, leading to monoenergetic ion production.
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