1 are designed [21,25–27]. Clarifying how to distinguish these trivial mechanisms from the 3D quantum Hall effect will be an interesting direction. 1d) and s7 with p-type carriers (Fig. The AFM state disappears at TN ∼ 21 K and the C = 1 QHE state can survive up to 45 K (Hall resistance plateau of 0.904 h/e2), much higher than TN. Since the position of Weyl points in momentum space and the topological Chern number of thin films depend sensitively on the out-of-lattice constant c = 3c0, structures with different c0 ranging from theoretical (⁠|${c_0} = 13.53$| Å) [11] to experimental (⁠|${c_0} = 13.6$| Å) [32] values were systematically studied and compared (Fig. 1d and e. These two transitions may mark the beginning and ending of the spin-flipping process. Figure 1: (Left) The quantum Hall effect (QHE) occurs in a two-dimensional electron system under a large applied magnetic field. This is why we call it a 3D quantum Hall effect. kx stands for (kx, ky) for the bulk and kx for the surface, respectively. With further application of a perpendicular magnetic field, the sample is supposed to enter the perfectly aligned FM state [19]. S5b). Uchida M, Nakazawa Y, Nishihaya S et al. . Rev. DOI: 10.4236/jmp.2013.411A1003 3,240 Downloads 4,702 Views Citations This article belongs to the Special Issue on Advances in Quantum Physics. The proposal employs topologically protected Fermi arcs and ‘wormhole’ tunneling via the Weyl nodes in a 3D topological semimetal. They cannot be regarded as 2D. Standard electron beam lithography in a FEI Helios NanoLab 600i Dual Beam System was used to define electrodes after spin-coating PMMA resist. The quantum Hall effect (or integer quantum Hall effect) is a quantized version of the Hall effect, observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields, in which the Hall resistance Rxy exhibits steps that take on the quantized values at certain level To put the benefits of the quantum Hall effect in the proper context, classical resistance metrology is addressed, in which the resistance is linked to a calculable capacitor, which provides traceability to the SI. © The Author(s) 2020. This indicates that QHE can be realized without the formation of LLs. Since the mBJ functional cannot be directly applied to describe systems with vacuum space, the tight-binding method was used to model thin films. The QHE in 2D electron systems with high mobility is originated from the formation of Landau levels (LLs) under strong external magnetic field. The Fermi surface of the surface states is known as the Fermi arcs (red and blue curves in Fig. 1a–d). By John K. Waters; 05/19/2020; A group of U.S. and German physicists have found surprising evidence that one of the most famous phenomena in modern physics, the quantum Hall effect, is "reincarnated" in topological superconductors that could be used to build fault-tolerant quantum computers. It represents good example of physical systems where quantization effect could be observed microscopically as a result of the interplay of the topology, interactions of electron with magnetic field, electron-electron interactions, and disorder. Note that it is theoretically challenging to accurately predict |$C( N )$|⁠, since the predicted |${\tilde {k}_W}$| depends sensitively on the exchange-correlational functional and the lattice structure. S1f). 1a. These two issues may explain the 2-fold and 4-fold degenerate Hall resistance plateaus observed in the experiments. Abstract. S5a and c. Temperature evolution of Ryx and Rxx in s2 with Vbg = 6.5 V is shown in Fig. For emerging physics and low-power-consumption electronics, the key issues are how to increase the working temperature and realize high Chern numbers (C > 1). J.G. The quantum anomalous Hall effect is defined as a quantized Hall effect realized in a system without an external magnetic field. Based on the mBJ functional [29], we systematically tested the influence of lattice parameter |${c_0}$| on band structure and |$C( N )$| (Fig. 3b and e) at various temperatures (the cyan spheres) and the peak value of the Rxx (T) curve (Fig. A review article about my career as a solid-state physicist has to focus on the quantum Hall effect (QHE). At a single surface, there is a complete 2D electron gas, formed by two time-reversed half-2D electron gases of the Fermi-arc surface states. More research will be necessary to verify the mechanism and realize the 3D quantum Hall effect in the future. Atomic force microscope measurements were carried out to determine the thickness of s6 (Fig. International Center for Quantum Materials, School of Physics, Peking University. MnBi2Te4 is a layered material which can be viewed as a layer of Bi2Te3 TI intercalated with an additional Mn-Te layer [11–20]. Figure 1g shows the schematic FM order and electronic structure of the C = 2 Chern insulator state with two chiral edge states across the band gap. 3 and Fig. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd. The dispersion prevents the quantization of the Hall conductance because the Fermi energy always crosses some 1D Landau bands whose conductance is not quantized. S9). B … Here we report the first experimental discovery of the high-Chern-number QHE without LLs above 10 K and C = 1 QHE without LLs above the Néel temperature (TN) in MnBi2Te4 devices. The discovery of QHE introduces the concept of topology into condensed matter physics and is extremely important to physical sciences and technologies. We review recent results concerning the spectrum of edge states in the quantum Hall effect in graphene. The quantum anomalous Hall effect is a novel manifestation of topological structure in many-electron systems and may have potential applications in … Sciences and technologies quantization of the University of Oxford figure 1b shows an Optical image of the two are! Microscope measurements were carried out to determine the thickness of FM MnBi2Te4 up new opportunities 8-SL ) 7-SL! The text 3 nm ) for the quantization of the 10-SL MnBi2Te4 device ( s6 ) with Hall geometry... In physics describing the behavior of electrons within a magnetic field, the number. Alternative mechanism of realizing QAHE through localization of band electrons was later proposed in 2003 [ 7 ] a Weyl. 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