论文标题
磁性拓扑结晶的发现
Discovery of magnetic topological crystals
论文作者
论文摘要
物质的拓扑阶段已经建立了一个新的物理范式，将量子现象带入了宏观量表，并托管了异国情调的新兴准粒子。在本论文中，我在理论上和实验上使用角度分辨光发射光谱（ARPES）在我的合作者中与我的第一座Weyl Semimetal TAAS一起证明，直接观察其新兴的Weyl fermions和拓扑的Fermi Fermi和拓扑表面状态[Science 349，6248（2015）;纳特。社区。 6，7373（2015）; PRL 116，066802（2016）]。接下来，我在手性晶体RHSI和COSI中发现了高级拓扑性手性手费，具有宽阔的拓扑能量窗口，动量空间中的最大分离和巨大的费米弧[Nature 567，500（2019）；纳特。垫。 17，978（2018）]。我在结构和拓扑性手性之间建立了自然关系，与稳健的拓扑状态相关，我们预测该状态支持四个单元的量化光质量效应[PRL 119，206401（2017）]。我还讨论了由交替拓扑和琐碎绝缘子组成的多层异质结构中的第一个量子拓扑超级晶格[Sci。 ADV。 3，E1501692（2017）]。每个界面隧道上的狄拉克锥体横跨层，形成了一个新兴的原子链，在该链中，狄拉克锥充当原子轨道。我实现了在超晶格中跳跃振幅的前所未有的控制，实现了拓扑相变。最后，我在Co $ _2 $ MNGA中发现了一个室温拓扑磁铁[Science 365，1278（2019）; PRL 119，156401（2017）]。我通过ARPE观察到拓扑Weyl线和鼓头表面状态，证明了拓扑不变，并由材料的固有磁性顺序支持。我还发现，co $ _2 $ mnga中的大型大厅效应来自Weyl线。我希望我对Co $ _2 $ MNGA的发现将拓扑磁性确立为凝聚态物理学的新领域。
Topological phases of matter have established a new paradigm in physics, bringing quantum phenomena to the macroscopic scale and hosting exotic emergent quasiparticles. In this thesis, I theoretically and experimentally demonstrate with my collaborators the first Weyl semimetal, TaAs, using angle-resolved photoemission spectroscopy (ARPES), directly observing its emergent Weyl fermions and topological Fermi arc surface states [Science 349, 6248 (2015); Nat. Commun. 6, 7373 (2015); PRL 116, 066802 (2016)]. Next, I discover high-degeneracy topological chiral fermions in the chiral crystals RhSi and CoSi, with wide topological energy window, maximal separation in momentum space and giant Fermi arcs [Nature 567, 500 (2019); Nat. Mat. 17, 978 (2018)]. I establish a natural relationship between the structural and topological chirality, associated with a robust topological state which we predict supports a four-unit quantized photogalvanic effect [PRL 119, 206401 (2017)]. I also discuss the first quantum topological superlattice, in multilayer heterostructures consisting of alternating topological and trivial insulators [Sci. Adv. 3, e1501692 (2017)]. The Dirac cones at each interface tunnel across layers, forming an emergent atomic chain where the Dirac cones serve as atomic orbitals. I achieve unprecedented control of hopping amplitudes within the superlattice, realizing a topological phase transition. Lastly, I discover a room-temperature topological magnet in Co$_2$MnGa [Science 365, 1278 (2019); PRL 119, 156401 (2017)]. I observe topological Weyl lines and drumhead surface states by ARPES, demonstrating a topological invariant supported by the material's intrinsic magnetic order. I also find that the large anomalous Hall effect in Co$_2$MnGa arises from the Weyl lines. I hope that my discovery of Co$_2$MnGa establishes topological magnetism as a new frontier in condensed matter physics.
