The quantum Hall effect (QHE) with quantized Hall resistance of h/νe2 starts the research on topological quantum states and lays the foundation of topology in physics. Afterwards, Haldane proposed the QHE without Landau levels, showing nonzero Chern number |C| = 1, which has been experimentally observed at relatively low temperatures. 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). Here, we report the experimental discovery of high-Chern-number QHE (C = 2) without Landau levels and C = 1 Chern insulator state displaying nearly quantized Hall resistance plateau above the Néel temperature in MnBi2Te4 devices. Our observations provide a new perspective on topological matter and open new avenues for exploration of exotic topological quantum states and topological phase transitions at higher temperatures.

Abstract2D magnetism plays a key role in both fundamental physics and potential device applications. However, the instability of the discovered 2D magnetic materials has been one main obstacle in deep research and potential application of 2D magnetism. Here, a localized magnetic moment induced by Pt vacancies in air‐stable type‐II Dirac semimetal PtSe2 flakes is reported. The localized magnetic moments give rise to the Kondo effect, evidenced by logarithmic increment of resistance with decreasing temperature and isotropic negative longitudinal magnetoresistance. Additionally, the induced magnetic moment and Kondo temperature appear to depend on thickness in the thinner samples (<10 nm). The small magnetocrystalline anisotropy revealed by first‐principles calculation indicates that the magnetic moments are randomly localized instead of long‐range ordered. The findings demonstrate a new means to induce magnetism in 2D non‐magnetic materials.

Unconventional quasiparticle excitations in condensed matter systems have become one of the most important research frontiers. Beyond twofold and fourfold degenerate Weyl and Dirac fermions, threefold, sixfold, and eightfold symmetry protected degeneracies have been predicted. However they remain challenging to realize in solid state materials. Here the charge density wave compound TaTe 4 is proposed to hold eightfold fermionic excitation and Dirac point in energy bands. High quality TaTe 4 single crystals are prepared, where the charge density wave is revealed by directly imaging the atomic structure and a pseudogap of about 45 meV on the surface. Shubnikov-de Haas oscillations of TaTe 4 are consistent with band structure calculation. Scanning tunneling microscopy/spectroscopy reveals atomic step edge states on the surface of TaTe 4 . This work uncovers that the charge density wave is able to induce new topological phases and sheds new light on the novel excitations in condensed matter materials.

Transition metal dichalcogenides, featuring layered structures, have aroused enormous interest as a platform for novel physical phenomena and a wide range of potential applications. Among them, special interest has been placed upon WTe2 and MoTe2, which exhibit non-trivial topology both in single layer and bulk as well as pressure induced or enhanced superconductivity. We study another distorted 1T material NbTe2 through systematic electrical transport measurements. Intrinsic superconductivity with onset transition temperature (𝑇 onset c ) up to 0.72 K is detected where the upper critical field (𝐻c) shows unconventional quasi-linear behavior, indicating spin-orbit coupling induced p-wave paring. Furthermore, a general model is proposed to fit the angledependent magnetoresistance, which reveals the Fermi surface anisotropy of NbTe2. Finally, non-saturating linear magnetoresistance up to 50 T is observed and attributed to the quantum limit transport.

Berry phase and Berry curvature play a key role in the development of topology in physics and do contribute to the transport properties in solid state systems. In this paper, we report the finding of novel nonzero Hall effect in topological material ZrTe5 flakes when in-plane magnetic field is parallel and perpendicular to the current. Surprisingly, both symmetric and antisymmetric components with respect to magnetic field are detected in the in-plane Hall resistivity. Further theoretical analysis suggests that the magnetotransport properties originate from the anomalous velocity induced by Berry curvature in a tilted Weyl semimetal. Our work not only enriches the Hall family but also provides new insights into the Berry phase effect in topological materials.