Quantized electric multipole insulators
TLDR
This work introduces a paradigm in which “nested” Wilson loops give rise to topological invariants that have been overlooked and opens a venue for the expansion of the classification of topological phases of matter.Abstract:
The Berry phase provides a modern formulation of electric polarization in crystals. We extend this concept to higher electric multipole moments and determine the necessary conditions and minimal models for which the quadrupole and octupole moments are topologically quantized electromagnetic observables. Such systems exhibit gapped boundaries that are themselves lower-dimensional topological phases. Furthermore, they host topologically protected corner states carrying fractional charge, exhibiting fractionalization at the boundary of the boundary. To characterize these insulating phases of matter, we introduce a paradigm in which “nested” Wilson loops give rise to topological invariants that have been overlooked. We propose three realistic experimental implementations of this topological behavior that can be immediately tested. Our work opens a venue for the expansion of the classification of topological phases of matter.read more
Citations
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Phonon-induced Floquet topological phases protected by space-time symmetries
TL;DR: In this article, the symmetry promotion action of a phonon drive was used to realize Floquet topological phases protected by space-time symmetry, which can be seen as a way to realize the phase transition.
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Chiral symmetry breaking of tight-binding models in coupled acoustic-cavity systems
TL;DR: In this article, the authors systematically studied the coupled acoustic-cavity system (CACS), which is an important acoustic platform for realizing tight-binding models (TBMs), and found that the length and number of coupling waveguides not only affect hopping, but also induce a perturbation to the onsite eigenfrequency, which can be attributed to the breaking of chiral symmetry in the TBM.
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Topological insulators and semimetals in classical magnetic systems
TL;DR: In this article, the authors provide an overview of current progress of topological phases in structured classical magnetism and discuss the experimental realization and detection of the edge states in both magnonic and solitonic crystals.
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Universal Approach to Magnetic Second-Order Topological Insulator
TL;DR: Using first-principles calculations, it is predicted that bismuthene on EuO(111) surface as the first realistic system for a two-dimensional magnetic SOTI, and explicitly demonstrate the existence of the protected corner states.
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Higher-order topological semimetal in phononic crystals
Qiang Wei,Xuewei Zhang,Weiyin Deng,Jiuyang Lu,Xueqin Huang,Mou Yan,Gang Chen,Zhengyou Liu,Suotang Jia +8 more
TL;DR: In this paper, a second-order topological Weyl semimetal was realized in a 3D phononic crystal, which possesses Weyl points in 3D momentum space, gapped surface states on the 2D surfaces and gapless hinge states on 1D hinges.
References
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New Method for High-Accuracy Determination of the Fine-Structure Constant Based on Quantized Hall Resistance
TL;DR: In this article, the Hall voltage of a two-dimensional electron gas, realized with a silicon metal-oxide-semiconductor field effect transistor, was measured and it was shown that the Hall resistance at particular, experimentally well-defined surface carrier concentrations has fixed values which depend only on the fine-structure constant and speed of light, and is insensitive to the geometry of the device.
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Maximally localized generalized Wannier functions for composite energy bands
Nicola Marzari,David Vanderbilt +1 more
TL;DR: In this paper, a method for determining the optimally localized set of generalized Wannier functions associated with a set of Bloch bands in a crystalline solid is presented, which is suitable for use in connection with conventional electronic-structure codes.
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