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Chen Q, Chen F, Pan Y, Cui C, Yan Q, Zhang L, Gao Z, Yang SA, Yu ZM, Chen H, Zhang B, Yang Y. Discovery of a maximally charged Weyl point. Nat Commun 2022; 13:7359. [PMID: 36450711 PMCID: PMC9712526 DOI: 10.1038/s41467-022-34978-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/14/2022] [Indexed: 12/03/2022] Open
Abstract
The hypothetical Weyl particles in high-energy physics have been discovered in three-dimensional crystals as collective quasiparticle excitations near two-fold degenerate Weyl points. Such momentum-space Weyl particles carry quantised chiral charges, which can be measured by counting the number of Fermi arcs emanating from the corresponding Weyl points. It is known that merging unit-charged Weyl particles can create new ones with more charges. However, only very recently has it been realised that there is an upper limit - the maximal charge number that a two-fold Weyl point can host is four - achievable only in crystals without spin-orbit coupling. Here, we report the experimental realisation of such a maximally charged Weyl point in a three-dimensional photonic crystal. The four charges support quadruple-helicoid Fermi arcs, forming an unprecedented topology of two non-contractible loops in the surface Brillouin zone. The helicoid Fermi arcs also exhibit the long-pursued type-II van Hove singularities that can reside at arbitrary momenta. This discovery reveals a type of maximally charged Weyl particles beyond conventional topological particles in crystals.
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Affiliation(s)
- Qiaolu Chen
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Fujia Chen
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Yuang Pan
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Chaoxi Cui
- grid.43555.320000 0000 8841 6246Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081 China ,grid.43555.320000 0000 8841 6246Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081 China
| | - Qinghui Yan
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Li Zhang
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Zhen Gao
- grid.263817.90000 0004 1773 1790Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055 China
| | - Shengyuan A. Yang
- grid.263662.50000 0004 0500 7631Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372 Singapore
| | - Zhi-Ming Yu
- grid.43555.320000 0000 8841 6246Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081 China ,grid.43555.320000 0000 8841 6246Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081 China
| | - Hongsheng Chen
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
| | - Baile Zhang
- grid.59025.3b0000 0001 2224 0361Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371 Singapore ,grid.59025.3b0000 0001 2224 0361Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798 Singapore
| | - Yihao Yang
- grid.13402.340000 0004 1759 700XInterdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027 China ,grid.13402.340000 0004 1759 700XInternational Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400 China ,grid.13402.340000 0004 1759 700XJinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099 China
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Zhang RW, Zhou X, Zhang Z, Ma DS, Yu ZM, Feng W, Yao Y. Weyl Monoloop Semi-Half-Metal and Tunable Anomalous Hall Effect. NANO LETTERS 2021; 21:8749-8755. [PMID: 34609886 DOI: 10.1021/acs.nanolett.1c02968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nodal monoloop, enjoying the cleanest scenario with a single loop, is recognized as the basic building block of intricate linked loops including chains, nets, and knots. Here, we explore the interplay of magnetic ordering and band topology in one system by introducing a brand-new quantum state, referred to as Weyl monoloop semi-half-metal, which is characterized by a single loop at the Fermi level stemming from the same spin channel. Such a nodal line Fermion, yielding 100% spin polarization, is protected by mirror (Mz) symmetry. As a prominent example, a realistic rutile-type metal fluorides LiV2F6 achieves the hitherto unmaterialized state, featuring fully spin-polarized ultraflat surface states. More interestingly, LiV2F6 has a "soft" ferromagnetic property, which is one of the desired systems to control the anomalous Hall effect by rotating the magnetization direction. Our findings offer a promising candidate for exploring the topology and magnetism with intriguing effects.
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Affiliation(s)
- Run-Wu Zhang
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
- Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Xiaodong Zhou
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
- Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Zeying Zhang
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Da-Shuai Ma
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
- Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Zhi-Ming Yu
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
- Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Wanxiang Feng
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
- Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Yugui Yao
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
- Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, China
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Wang J, Zhao M, Liu W, Guan F, Liu X, Shi L, Chan CT, Zi J. Shifting beams at normal incidence via controlling momentum-space geometric phases. Nat Commun 2021; 12:6046. [PMID: 34663832 PMCID: PMC8523713 DOI: 10.1038/s41467-021-26406-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 09/27/2021] [Indexed: 11/08/2022] Open
Abstract
When hitting interfaces between two different media, light beams may undergo small shifts. Such beam shifts cannot be described by the geometrical optics based on Snell's law and their underlying physics has attracted much attention. Conventional beam shifts like Goos-Hänchen shifts and Imbert-Fedorov shifts not only require obliquely incident beams but also are mostly very small compared to the wavelength and waist size of the beams. Here we propose a method to realize large and controllable polarization-dependent lateral shifts for normally incident beams with photonic crystal slabs. As a proof of the concept, we engineer the momentum-space geometric phase distribution of a normally incident beam by controlling its interaction with a photonic crystal slab whose momentum-space polarization structure is designed on purpose. The engineered geometric phase distribution is designed to result in a large shift of the beam. We fabricate the designed photonic crystal slab and directly observe the beam shift, which is ~5 times the wavelength and approaches the waist radius. Based on periodic structures and only requiring simple manipulation of symmetry, our proposed method is an important step towards practical applications of beam shifting effects.
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Affiliation(s)
- Jiajun Wang
- State Key Laboratory of Surface Physics, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, 200433, Shanghai, China
| | - Maoxiong Zhao
- State Key Laboratory of Surface Physics, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, 200433, Shanghai, China
| | - Wenzhe Liu
- State Key Laboratory of Surface Physics, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, 200433, Shanghai, China.
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
| | - Fang Guan
- State Key Laboratory of Surface Physics, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, 200433, Shanghai, China
| | - Xiaohan Liu
- State Key Laboratory of Surface Physics, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, 200433, Shanghai, China
| | - Lei Shi
- State Key Laboratory of Surface Physics, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, 200433, Shanghai, China.
| | - C T Chan
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jian Zi
- State Key Laboratory of Surface Physics, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Department of Physics, Fudan University, 200433, Shanghai, China.
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Zhou F, Liu Y, Kuang M, Wang P, Wang J, Yang T, Wang X, Cheng Z, Zhang G. Time-reversal-breaking Weyl nodal lines in two-dimensional A 3C 2 (A = Ti, Zr, and Hf) intrinsically ferromagnetic materials with high Curie temperature. NANOSCALE 2021; 13:8235-8241. [PMID: 33885113 DOI: 10.1039/d1nr00139f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Most materials that feature nontrivial band topology are spin-degenerate and three dimensional, strongly restricting them from application in spintronic nanodevices. Hence, two-dimensional (2D) intrinsically spin-polarized systems with rich topological elements are still in extreme scarcity. Here, 2D A3C2 (A = Ti, Zr, and Hf) materials with the P6[combining macron]m2 type structure are reported as new ferromagnetic materials with intrinsic magnetism and good stability. Unlike the Weyl nodal lines existing in nonmagnetic 2D systems, A3C2 hosts time-reversal-breaking Weyl nodal rings (two Γ-centered, one K-centered, and one K'-centered) without spin-orbit coupling (SOC). These nodal rings still remained under SOC with magnetization along the z direction (easy magnetization axis). More interestingly, the Curie temperatures (TC) of A3C2 were determined based on the Monte Carlo simulation. Ti3C2 features an extraordinary TC (above 800 K), and those of Zr3C2 and Hf3C2 are above room temperature. Therefore, A3C2 materials are excellent platforms to study magnetic Weyl nodal lines in high TC ferromagnetic 2D materials.
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Affiliation(s)
- Feng Zhou
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
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Meng W, Liu W, Zhang X, Liu Y, Dai X, Liu G. Novel topological states of nodal points and nodal rings in 2D planar octagon TiB 4. NANOSCALE 2021; 13:3194-3200. [PMID: 33527968 DOI: 10.1039/d0nr08015b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Topological states of matter in two-dimensional (2D) materials have received increasing attention due to their potential applications in nanoscale spintronics. Here, we report the presence of unique topological electronic properties in a 2D planar octagon TiB4 compound. Particularly, without considering the spin-orbit coupling (SOC), we found that the material showed a coexistence of novel quadratic node (QN), and two different types of nodal rings (NRs), namely type-I and type-II. The protection mechanism of fermions has been fully clarified in this study. Furthermore, these fermions showed clear edge states. It is worth noting that QN had a topological charge of 2 since it is different from linear nodes and exhibit clear Fermi arc edge states. Under lattice strain, we found that the system could further exhibit rich topological phase transition. When SOC was included, we determined that these crossing points open very tiny energy gaps, which were smaller than previously reported 3D and 2D examples. These results show that monolayer TiB4 is an excellent nodal point and nodal ring semimetal, which also provides a feasible member for studying potential entanglements among multiple fermions.
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Affiliation(s)
- Weizhen Meng
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China.
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