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Li Z, Pan B, Zhou P, Kang R, He S, Peng X, Sun L. Symmetry-enforced fourfold degenerate phonons in noncentrosymmetric space groups. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:165701. [PMID: 38190732 DOI: 10.1088/1361-648x/ad1bf7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 01/08/2024] [Indexed: 01/10/2024]
Abstract
Multifold degenerate phonons have received much attention due to their nontrivial monopole topological charge and fascinating boundary states. Although Yuet alrecently provides a comprehensive list of all potential nodal points for systems with specific space groups (SGs) (2022Sci. Bull.67375). However, our understanding of the fundamental mechanisms that give rise to the formation of fourfold-degenerate (FD) phonons is still limited. In this paper, we have directed our research towards investigating the generation mechanism of these FD phonons in noncentrosymmetric SGs. Using symmetry arguments andk⋅pmodel analysis, we have classified them into two categories: the first origins from the commutation/anticommutation relation of the little cogroup operations, and the second associates to the combination of threefold rotation, mirror and time-reversal symmetries. Moreover, the band dispersions of the FD phonons in the first group are required to be linear, whereas the band dispersions of the FD phonons in the second category may be quadratic. On the basis of first-principles calculations, we propose that K2Mg2O3and Na4SnSe4are representative candidates for the two categories, respectively. Furthermore, for each SG with fourfold degenerate phonons, we propose corresponding materials that must host the FD points. Our work not only deepens our understanding of the mechanisms underlying the formation of these FD phonons, but it also proposes practical materials for observing FD phonons in crystalline systems without inversion symmetry.
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Affiliation(s)
- Zehou Li
- Hunan Provincial Key laboratory of Thin Film Materials and Devices, School of Material Sciences and Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China
- Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, School of Physics and Optoelectronics, Xiangtan University, Hunan 411105, People's Republic of China
| | - Baoru Pan
- Hunan Provincial Key laboratory of Thin Film Materials and Devices, School of Material Sciences and Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China
- Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, School of Physics and Optoelectronics, Xiangtan University, Hunan 411105, People's Republic of China
| | - Pan Zhou
- Hunan Provincial Key laboratory of Thin Film Materials and Devices, School of Material Sciences and Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Ruirong Kang
- Hunan Provincial Key laboratory of Thin Film Materials and Devices, School of Material Sciences and Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Shenda He
- Hunan Provincial Key laboratory of Thin Film Materials and Devices, School of Material Sciences and Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Xiangyang Peng
- Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, School of Physics and Optoelectronics, Xiangtan University, Hunan 411105, People's Republic of China
| | - Lizhong Sun
- Hunan Provincial Key laboratory of Thin Film Materials and Devices, School of Material Sciences and Engineering, Xiangtan University, Xiangtan 411105, People's Republic of China
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Ding G, Sun T, Wang X. Ideal nodal-net, nodal-chain, and nodal-cage phonons in some realistic materials. Phys Chem Chem Phys 2022; 24:11175-11182. [PMID: 35481499 DOI: 10.1039/d2cp00731b] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The topological interpretation of phonons provides a new platform for new concepts in phonon physics. While reports on topological electronic excitations are plenty, the number of reports on phonons is extremely limited. In this paper, we present some realistic materials as examples and demonstrate the appearance of ideal nodal-net, nodal-chain, and nodal-cage phonons in these materials based on first-principle calculations; Pna21 LiAlSe2 has a nodal-net phonon, which is composed of two nodal-chain phonons along the U-R and U-Z directions; Pnma NaMgH3 has a nodal-chain phonon in the extended Brillouin zone (BZ), which comprises two Weyl nodal-ring phonons in the kx-kz and kx-ky planes. Moreover, P42/ncm AuBr has a nodal-cage phonon, which is composed of nodal-line phonons in the kz = 0, kz = π, kx = 0, and ky = 0 planes. Because the presented phonon bands and phonon surface states in these materials are quite clean, they can be easily detected in experiments. Our research results provide an ideal platform for realising complex geometric shapes (formed by nodal lines) in the momentum space of phonons.
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Affiliation(s)
- Guangqian Ding
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing, 400065, China
| | - Tingting Sun
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
| | - Xiaotian Wang
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China.
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Ding G, SUN T, Surucu G, Surucu O, Gencer A, Wang X. Complex nodal structure phonons formed by open and closed nodal lines in CoAsS and Na2CuP solids. Phys Chem Chem Phys 2022; 24:17210-17216. [DOI: 10.1039/d2cp01992b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Topological phononic states with nodal lines have not only updated our knowledge of the phases of matter in a fundamental way, they have also become a major frontier research direction...
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