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Wang H, Xu W, Zhu Z, Yang B. Photonic Weyl Waveguide and Saddle-Chips-like Modes. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:620. [PMID: 38607154 PMCID: PMC11013772 DOI: 10.3390/nano14070620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 03/21/2024] [Accepted: 03/28/2024] [Indexed: 04/13/2024]
Abstract
Topological Weyl semimetals are characterized by open Fermi arcs on their terminal surfaces, these materials not only changed accepted concepts of the Fermi loop but also enabled many exotic phenomena, such as one-way propagation. The key prerequisite is that the two terminal surfaces have to be well separated, i.e., the Fermi arcs are not allowed to couple with each other. Thus, their interaction was overlooked before. Here, we consider coupled Fermi arcs and propose a Weyl planar waveguide, wherein we found a saddle-chips-like hybridized guiding mode. The hybridized modes consist of three components: surface waves from the top and bottom surfaces and bulk modes inside the Weyl semimetal. The contribution of these three components to the hybridized mode appears to be z-position-dependent rather than uniform. Beyond the conventional waveguide framework, those non-trivial surface states, with their arc-type band structures, exhibit strong selectivity in propagation direction, providing an excellent platform for waveguides. Compared with the conventional waveguide, the propagation direction of hybridized modes exhibits high z-position-dependency. For example, when the probe plane shifts from the top interface to the bottom interface, the component propagating horizontally becomes dimmer, while the component propagating vertically becomes brighter. Experimentally, we drilled periodic holes in metal plates to sandwich an ideal Weyl meta-crystal and characterize the topological guiding mode. Our study shows the intriguing behaviors of topological photonic waveguides, which could lead to beam manipulation, position sensing, and even 3D information processing on photonic chip. The Weyl waveguide also provides a platform for studying the coupling and the interaction between surface and bulk states.
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Affiliation(s)
- Hanyu Wang
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.W.); (W.X.)
- Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Wei Xu
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.W.); (W.X.)
- Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Zhihong Zhu
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.W.); (W.X.)
- Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Biao Yang
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.W.); (W.X.)
- Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
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Wang H, Xu W, Wei Z, Wang Y, Wang Z, Cheng X, Guo Q, Shi J, Zhu Z, Yang B. Twisted photonic Weyl meta-crystals and aperiodic Fermi arc scattering. Nat Commun 2024; 15:2440. [PMID: 38499579 PMCID: PMC10948390 DOI: 10.1038/s41467-024-46759-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 03/08/2024] [Indexed: 03/20/2024] Open
Abstract
As a milestone in the exploration of topological physics, Fermi arcs bridging Weyl points have been extensively studied. Weyl points, as are Fermi arcs, are believed to be only stable when preserving translation symmetry. However, no experimental observation of aperiodic Fermi arcs has been reported so far. Here, we continuously twist a bi-block Weyl meta-crystal and experimentally observe the twisted Fermi arc reconstruction. Although both the Weyl meta-crystals individually preserve translational symmetry, continuous twisting operation leads to the aperiodic hybridization and scattering of Fermi arcs on the interface, which is found to be determined by the singular total reflection around Weyl points. Our work unveils the aperiodic scattering of Fermi arcs and opens the door to continuously manipulating Fermi arcs.
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Affiliation(s)
- Hanyu Wang
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, 410073, China
- Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha, 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha, 410073, China
| | - Wei Xu
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, 410073, China
- Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha, 410073, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha, 410073, China
| | - Zeyong Wei
- Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Yiyuan Wang
- Key Laboratory of In-Fiber Integrated Optics of Ministry of Education, College of Physics and Optoelectronic Engineering, Harbin Engineering University, Harbin, 150001, China
| | - Zhanshan Wang
- Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Xinbin Cheng
- Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Qinghua Guo
- School of Physics and Electronics, Hunan University, Changsha, 410082, China.
| | - Jinhui Shi
- Key Laboratory of In-Fiber Integrated Optics of Ministry of Education, College of Physics and Optoelectronic Engineering, Harbin Engineering University, Harbin, 150001, China.
| | - Zhihong Zhu
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, 410073, China.
- Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha, 410073, China.
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha, 410073, China.
| | - Biao Yang
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, 410073, China.
- Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha, 410073, China.
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha, 410073, China.
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Hu J, Yu F, Luo A, Pan XH, Zou J, Liu X, Xu G. Chiral Topological Superconductivity in Superconductor-Obstructed Atomic Insulator-Ferromagnetic Insulator Heterostructures. PHYSICAL REVIEW LETTERS 2024; 132:036601. [PMID: 38307042 DOI: 10.1103/physrevlett.132.036601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 12/08/2023] [Indexed: 02/04/2024]
Abstract
Implementing topological superconductivity (TSC) and Majorana states (MSs) is one of the most significant and challenging tasks in both fundamental physics and topological quantum computations. In this work, taking the obstructed atomic insulator (OAI) Nb_{3}Br_{8}, s-wave superconductor (SC) NbSe_{2}, and ferromagnetic insulator (FMI) CrI_{3} as an example, we propose a new setup to realize the 2D chiral TSC and MSs in the SC/OAI/FMI heterostructure, which could avoid the subband problem effectively and has the advantage of huge Rashba spin-orbit coupling. As a result, the TSC phase can be stabilized in a wide region of chemical potential and Zeeman splitting, and four distinct TSC phases with superconducting Chern number N=-1,-2,-3, 3 can be achieved. Moreover, a 2D Bogoliubov-de Gennes Hamiltonian based on the triangular lattice of obstructed Wannier charge centers, combined with the s-wave superconductivity paring and Zeeman splitting, is constructed to understand the whole topological phase diagram analytically. These results expand the application of OAIs and pave a new way to realize the TSC and MSs with unique advantages.
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Affiliation(s)
- Jingnan Hu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Fei Yu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Aiyun Luo
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiao-Hong Pan
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Jinyu Zou
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xin Liu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
- Wuhan Institute of Quantum Technology, Wuhan 430206, China
| | - Gang Xu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
- Wuhan Institute of Quantum Technology, Wuhan 430206, China
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4
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Giwa R, Hosur P. Superconductor Vortex Spectrum Including Fermi Arc States in Time-Reversal Symmetric Weyl Semimetals. PHYSICAL REVIEW LETTERS 2023; 130:156402. [PMID: 37115867 DOI: 10.1103/physrevlett.130.156402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 12/21/2022] [Accepted: 03/27/2023] [Indexed: 06/19/2023]
Abstract
Using semiclassics to surmount the hurdle of bulk-surface inseparability, we derive the superconductor vortex spectrum in nonmagnetic Weyl semimetals and show that it stems from the Berry phase of orbits made of Fermi arcs on opposite surfaces and bulk chiral modes. Tilting the vortex transmutes it between bosonic, fermionic, and supersymmetric, produces periodic peaks in the density of states that signify novel nonlocal Majorana modes, and yields a thickness-independent spectrum at magic "magic angles." We propose (Nb,Ta)P as candidate materials and tunneling spectroscopy as the ideal experiment.
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Affiliation(s)
- Rauf Giwa
- University of Houston, Houston, Texas 77204, USA
| | - Pavan Hosur
- University of Houston, Houston, Texas 77204, USA
- Texas Center for Superconductivity at the University of Houston, Houston, Texas 77204, USA
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Hu LH, Zhang RX. Topological superconducting vortex from trivial electronic bands. Nat Commun 2023; 14:640. [PMID: 36746955 PMCID: PMC9902606 DOI: 10.1038/s41467-023-36347-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 01/24/2023] [Indexed: 02/08/2023] Open
Abstract
Superconducting vortices are promising traps to confine non-Abelian Majorana quasi-particles. It has been widely believed that bulk-state topology, of either normal-state or superconducting ground-state wavefunctions, is crucial for enabling Majorana zero modes in solid-state systems. This common belief has shaped two major search directions for Majorana modes, in either intrinsic topological superconductors or trivially superconducting topological materials. Here we show that Majorana-carrying superconducting vortex is not exclusive to bulk-state topology, but can arise from topologically trivial quantum materials as well. We predict that the trivial bands in superconducting HgTe-class materials are responsible for inducing anomalous vortex topological physics that goes beyond any existing theoretical paradigms. A feasible scheme of strain-controlled Majorana engineering and experimental signatures for vortex Majorana modes are also discussed. Our work provides new guidelines for vortex-based Majorana search in general superconductors.
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Affiliation(s)
- Lun-Hui Hu
- grid.411461.70000 0001 2315 1184Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN 37996 USA ,grid.411461.70000 0001 2315 1184Institute for Advanced Materials and Manufacturing, The University of Tennessee, Knoxville, TN 37920 USA
| | - Rui-Xing Zhang
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN, 37996, USA. .,Institute for Advanced Materials and Manufacturing, The University of Tennessee, Knoxville, TN, 37920, USA. .,Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN, 37996, USA.
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Zhang Y, Qin S, Jiang K, Hu J. Gapless vortex bound states in superconducting topological semimetals. Natl Sci Rev 2023; 10:nwac121. [PMID: 36935934 PMCID: PMC10016197 DOI: 10.1093/nsr/nwac121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 12/13/2021] [Accepted: 02/14/2022] [Indexed: 11/14/2022] Open
Abstract
We find that the vortex bound states in superconducting topological semimetals are gapless owing to topological massless excitations in their normal states. We demonstrate this universal result in a variety of semimetals, including Dirac and Weyl semimetals, three-fold degenerate spin-1 fermions, spin-3/2 Rarita-Schwinger-Weyl fermion semimetals and other exotic fermion semimetals. The formation of these gapless bound states is closely related to their Andreev specular reflection and propagating Andreev modes in π-phase superconductor-normal metal-superconductor junctions. We further demonstrate that these gapless states are topologically protected and can be derived from a topological pumping process.
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Hu LH, Wu X, Liu CX, Zhang RX. Competing Vortex Topologies in Iron-Based Superconductors. PHYSICAL REVIEW LETTERS 2022; 129:277001. [PMID: 36638298 DOI: 10.1103/physrevlett.129.277001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
In this Letter, we establish a new theoretical paradigm for vortex Majorana physics in the recently discovered topological iron-based superconductors (TFeSCs). While TFeSCs are widely accepted as an exemplar of topological insulators (TIs) with intrinsic s-wave superconductivity, our theory implies that such a common belief could be oversimplified. Our main finding is that the normal-state bulk Dirac nodes, usually ignored in TI-based vortex Majorana theories for TFeSCs, will play a key role of determining the vortex state topology. In particular, the interplay between TI and Dirac nodal bands will lead to multiple competing topological phases for a superconducting vortex line in TFeSCs, including an unprecedented hybrid topological vortex state that carries both Majorana bound states and a gapless dispersion. Remarkably, this exotic hybrid vortex phase generally exists in the vortex phase diagram for our minimal model for TFeSCs and is directly relevant to TFeSC candidates such as LiFeAs. When the fourfold rotation symmetry is broken by vortex-line tilting or curving, the hybrid vortex gets topologically trivialized and becomes Majorana free, which could explain the puzzle of ubiquitous trivial vortices observed in LiFeAs. The origin of the Majorana signal in other TFeSC candidates such as FeTe_{x}Se_{1-x} and CaKFe_{4}As_{4} is also interpreted within our theory framework. Our theory sheds new light on theoretically understanding and experimentally engineering Majorana physics in high-temperature iron-based systems.
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Affiliation(s)
- Lun-Hui Hu
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Institute for Advanced Materials and Manufacturing, The University of Tennessee, Knoxville, Tennessee 37920, USA
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Xianxin Wu
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Chao-Xing Liu
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Rui-Xing Zhang
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Institute for Advanced Materials and Manufacturing, The University of Tennessee, Knoxville, Tennessee 37920, USA
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, USA
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8
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Shang T, Zhao J, Hu LH, Ma J, Gawryluk DJ, Zhu X, Zhang H, Zhen Z, Yu B, Xu Y, Zhan Q, Pomjakushina E, Shi M, Shiroka T. Unconventional superconductivity in topological Kramers nodal-line semimetals. SCIENCE ADVANCES 2022; 8:eabq6589. [PMID: 36306356 PMCID: PMC9616505 DOI: 10.1126/sciadv.abq6589] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 09/09/2022] [Indexed: 06/16/2023]
Abstract
Crystalline symmetry is a defining factor of the electronic band topology in solids, where many-body interactions often induce a spontaneous breaking of symmetry. Superconductors lacking an inversion center are among the best systems to study such effects or even to achieve topological superconductivity. Here, we demonstrate that TRuSi materials (with T a transition metal) belong to this class. Their bulk normal states behave as three-dimensional Kramers nodal-line semimetals, characterized by large antisymmetric spin-orbit couplings and by hourglass-like dispersions. Our muon-spin spectroscopy measurements show that certain TRuSi compounds spontaneously break the time-reversal symmetry at the superconducting transition, while unexpectedly showing a fully gapped superconductivity. Their unconventional behavior is consistent with a unitary (s + ip) pairing, reflecting a mixture of spin singlets and spin triplets. By combining an intrinsic time-reversal symmetry-breaking superconductivity with nontrivial electronic bands, TRuSi compounds provide an ideal platform for investigating the rich interplay between unconventional superconductivity and the exotic properties of Kramers nodal-line/hourglass fermions.
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Affiliation(s)
- Tian Shang
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Jianzhou Zhao
- Co-Innovation Center for New Energetic Materials, Southwest University of Science and Technology, Mianyang 621010, China
| | - Lun-Hui Hu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA
| | - Junzhang Ma
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong
| | - Dariusz Jakub Gawryluk
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Xiaoyan Zhu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Hui Zhang
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Zhixuan Zhen
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Bocheng Yu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Yang Xu
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Qingfan Zhan
- Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Ekaterina Pomjakushina
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Ming Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Toni Shiroka
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich, Switzerland
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