2,432 results on '"Electron–phonon coupling"'
Search Results
2. Prediction of high-Tc phonon-mediated superconductivity with strong Ising spin-orbit coupling in monolayer WNO
- Author
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Liu, Zhengtao, Zhang, Zihan, Ma, Tiancheng, Dong, Guiyan, Cai, Jialiang, Cui, Tian, and Duan, Defang
- Published
- 2025
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3. Distinct ultrafast dynamics of bilayer and trilayer nickelate superconductors regarding the density-wave-like transitions
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Li, Yidian, Cao, Yantao, Liu, Liangyang, Peng, Pai, Lin, Hao, Pei, Cuiying, Zhang, Mingxin, Wu, Heng, Du, Xian, Zhao, Wenxuan, Zhai, Kaiyi, Zhang, Xuefeng, Zhao, Jinkui, Lin, Miaoling, Tan, Pingheng, Qi, Yanpeng, Li, Gang, Guo, Hanjie, Yang, Luyi, and Yang, Lexian
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- 2025
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4. Optical characterization of the charge density wave phase of 9R BaRuO3 thin film
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Nam, Hyungwon, Kim, Dongwook, Lee, Sang A, Ok, Jong Mok, Choi, Woo Seok, and Moon, S.J.
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- 2025
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5. Superconductivity of the two-dimensional MB2C2 (M = 3d, 4d) monolayers
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Wu, Shan-Shan, Yang, Chuan-Lu, Li, Xiaohu, Liu, Yuliang, Zhao, Wenkai, and Gao, Feng
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- 2025
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6. Giant phonon anomaly in topological nodal-line semimetals
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Zhou, Zizhen, Yang, Xiaolong, Wang, Honghui, Han, Guang, Lu, Xu, Wang, Guoyu, Wang, Rui, and Zhou, Xiaoyuan
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- 2025
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7. Hotspot and nonequilibrium thermal transport in AlGaN/GaN FinFET: A coupled electron-phonon Monte Carlo simulation study
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Hu, Baoyi, Wang, Zhaoliang, Xu, Ke, and Tang, Dawei
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- 2025
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8. Electron–phonon coupling analysis and phonon-assisted laser wavelength extension in mid-infrared Tm:YAP crystal
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Li, Qianwen, Liang, Fei, Liu, Yuxiao, Si, Huichen, Pan, Zhongben, Lu, Dazhi, Yu, Haohai, and Zhang, Huaijin
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- 2025
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9. The effect of electron-phonon coupling on the photoluminescence properties of zinc-based halides
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Li, Zheyu, Li, Huwei, Li, Yao, Fu, Xinyu, Yue, Hongxia, Yang, Qingxing, Feng, Jing, Wang, Xinyu, and Zhang, Hongjie
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- 2025
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10. Electron–phonon coupling in Mott insulators
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Nagaosa, Naoto
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- 2025
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11. Investigation of the physical and superconductivity properties of Ni[formula omitted]AC (A: Mg, Zn and Cd)
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Zafer, T., Kurtuluş, F., Salimov, R., and Karaca, E.
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- 2025
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12. Exploring Heusler superconducting properties for Ni2ZrAl and Ni2ZrGa Heusler compounds: First principal insight
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Mahdjouba, Khatiri, Yahia, Bourourou, Fares, Faid, Abdelilah, Fadla Mohamed, and Mohammed, Bouchenafa
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- 2024
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13. Electron–phonon coupling and non-equilibrium thermal conduction in ultra-fast heating systems
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Zhang, Chuang, Guo, Rulei, Lian, Meng, and Shiomi, Junichiro
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- 2024
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14. Superconductivity in transition metal carbides, TaC and HfC: A density functional theory study with local, semilocal, and nonlocal exchange–correlation functionals
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Azam, Muhammad, Shahbaz, Muhammad, Habeeb-ur-Rehman, and Khan, Numan
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- 2024
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15. Polaronic corrections on magnetization and thermodynamic properties of electron–electron in 2D systems with Rashba spin–orbit coupling
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Lakaal, K., Kria, M., El Hamdaoui, J., Varsha, Prasad, V., Nautiyal, Vijit V., El-Yadri, M., Pérez, L.M., Laroze, D., and Feddi, E.
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- 2022
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16. Electron–Phonon Coupling in Copper-Substituted Lead Phosphate Apatite
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Tyner, Alexander C, Griffin, Sinéad M, and Balatsky, Alexander V
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Physical Sciences ,Condensed Matter Physics ,Electron–phonon coupling ,First-principles ,Superconductivity ,MSD-Theory ,Mathematical Physics ,Classical Physics ,General Physics ,Classical physics ,Condensed matter physics - Abstract
Recent reports of room-temperature, ambient pressure superconductivity in copper-substituted lead phosphate apatite, commonly referred to as LK99, have prompted numerous theoretical and experimental studies into its properties. As the electron-phonon interaction is a common mechanism for superconductivity, the electron-phonon coupling strength is an important quantity to compute for LK99. In this work, we compare the electron-phonon coupling strength among the proposed compositions of LK99. The results of our study are in alignment with the conclusion that LK99 is a candidate for low-temperature, not room-temperature, superconductivity if electron-phonon interaction is to serve as the mechanism.
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- 2024
17. Chemical bonding dictates drastic critical temperature difference in two seemingly identical superconductors.
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Lavroff, Robert H, Munarriz, Julen, Dickerson, Claire E, Munoz, Francisco, and Alexandrova, Anastassia N
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Physical Sciences ,Chemical Sciences ,Physical Chemistry ,Condensed Matter Physics ,borides ,chemical bonding ,electron–phonon coupling ,superconductivity - Abstract
Though YB6 and LaB6 share the same crystal structure, atomic valence electron configuration, and phonon modes, they exhibit drastically different phonon-mediated superconductivity. YB6 superconducts below 8.4 K, giving it the second-highest critical temperature of known borides, second only to MgB2. LaB6 does not superconduct until near-absolute zero temperatures (below 0.45 K), however. Though previous studies have quantified the canonical superconductivity descriptors of YB6's greater Fermi-level (Ef) density of states and higher electron-phonon coupling (EPC), the root of this difference has not been assessed with full detail of the electronic structure. Through chemical bonding, we determine low-lying, unoccupied 4f atomic orbitals in lanthanum to be the key difference between these superconductors. These orbitals, which are not accessible in YB6, hybridize with π B-B bonds and bring this π-system lower in energy than the σ B-B bonds otherwise at Ef. This inversion of bands is crucial: the optical phonon modes we show responsible for superconductivity cause the σ-orbitals of YB6 to change drastically in overlap, but couple weakly to the π-orbitals of LaB6. These phonons in YB6 even access a crossing of electronic states, indicating strong EPC. No such crossing in LaB6 is observed. Finally, a supercell (the M k-point) is shown to undergo Peierls-like effects in YB6, introducing additional EPC from both softened acoustic phonons and the same electron-coupled optical modes as in the unit cell. Overall, we find that LaB6 and YB6 have fundamentally different mechanisms of superconductivity, despite their otherwise near-identity.
- Published
- 2024
18. Effects of Homogeneous Doping on Electron–Phonon Coupling in SrTiO 3.
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Park, Minwoo and Chung, Suk Bum
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ANGULAR momentum (Mechanics) , *CARRIER density , *DENSITY functional theory , *CRITICAL temperature , *ELECTRON pairs - Abstract
Bulk n-type SrTiO3 (STO) has long been known to possess a superconducting ground state at an exceptionally dilute carrier density. This has raised questions about the applicability of the BCS-Eliashberg paradigm with its underlying adiabatic assumption. However, recent experimental reports have set the pairing gap to the critical temperature ( T c ) ratio at the BCS value for superconductivity in Nb-doped STO, even though the adiabaticity condition the BCS pairing requires is satisfied over the entire superconducting dome only by the lowest branch of optical phonons. In spite of the strong implications these reports have on specifying the pairing glue, they have not proved sufficient in explaining the magnitude of the optimal doping. This motivated us to apply density functional theory to Nb-doped STO to analyze how the phonon band structures and the electron–phonon coupling evolve with doping. To describe the very low doping concentration, we tuned the homogeneous background charge, from which we obtained a first-principles result on the doping-dependent phonon frequency that is in good agreement with experimental data for Nb-doped STO. Using the EPW code, we obtain the doping-dependent phonon dispersion and the electron–phonon coupling strength. Within the framework of our calculation, we found that the electron–phonon coupling forms a dome in a doping range lower than the experimentally observed superconducting dome of the Nb-doped STO. Additionally, we examined the doping dependence of both the orbital angular momentum quenching in the electron–phonon coupling and the phonon displacement correlation length and found the former to have a strong correlation with our electron–phonon coupling in the overdoped region. [ABSTRACT FROM AUTHOR]
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- 2025
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19. Raman and Photoluminescence Studies of Quasiparticles in van der Waals Materials.
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AL-Makeen, Mansour M., Biack, Mario H., Guo, Xiao, Xie, Haipeng, and Huang, Han
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OPTOELECTRONIC devices , *QUASIPARTICLES , *PHONONS , *ELECTRONIC equipment , *OPTICAL properties - Abstract
Two-dimensional (2D) layered materials have received much attention due to the unique properties stemming from their van der Waals (vdW) interactions, quantum confinement, and many-body interactions of quasi-particles, which drive their exotic optical and electronic properties, making them critical in many applications. Here, we review our past years' findings, focusing on many-body interactions in 2D layered materials, including phonon anharmonicity, electron–phonon coupling (e-ph), exciton dynamics, and phonon anisotropy based on temperature (polarization)-dependent Raman spectroscopy and Photoluminescence (PL). Our review sheds light on the role of quasi-particles in tuning the material properties, which could help optimize 2D materials for future applications in electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]
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- 2025
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20. Unveiling the Unusual Electron–Phonon Interaction and Quasi‐Particle Dynamics in type‐II Weyl Semimetal NbIrTe4.
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Sun, Kaiwen, Liu, Xiangqi, Wang, Chen, Lin, Xian, Suo, Peng, Guo, Yanfeng, and Ma, Guohong
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NONLINEAR optics , *PHONONS , *ANISOTROPY , *PHOTOEXCITATION , *SEMIMETALS , *OPTOELECTRONIC devices , *POLARONS - Abstract
Layered ternary type‐II Weyl semimetals demonstrate promising applications in high‐performance and broadband optoelectronics, therefore it is crucial to gain insights into their photocarriers' dynamics. In this work, the probing polarization dependence of non‐equilibrium dynamics in NbIrTe4 is investigated by using transient reflectivity spectroscopy. Following photoexcitation at 3.18 eV, the dynamical response of 1.59 eV probe pulse exhibits a strong dependence on probe polarization. The relaxation comprises two components: a rapid recovery of ≈0.6 ps attributed to the electron–phonon scattering, and an anomalous slow recovery spanning hundreds of picoseconds attributed to the photoinduced quasi‐particle. The polarization dependence of rapid relaxation time τ is indicative of the in‐plane anisotropy of electron–phonon coupling in NbIrTe4. The slow relaxation modulated by a latest reported 16 cm−1 coherent phonon also shows strong probing polarization dependence, further revealing the anisotropic nature of electron–phonon coupling and the possibility of anisotropic lattice distortion, as well as photoinduced polaron, under ultrafast photoexcitation in NbIrTe4. The dynamical anisotropy in NbIrTe4 has provided valuable guidance for the application of NbIrTe4 in polarization‐sensitive nonlinear optics or optoelectronic devices and offers insights into the unique carrier transport as well as phonon transport properties of this newly established topological material. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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21. Regulating Electron‐Phonon Coupling by Solid Additive for Efficient Organic Solar Cells.
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Ge, Zhongwei, Qiao, Jiawei, Li, Yun, Song, Jiali, Duan, Xiaopeng, Fu, Zhen, Hu, Haixia, Yang, Renqiang, Yin, Hang, Hao, Xiaotao, and Sun, Yanming
- Subjects
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ELECTRON-phonon interactions , *SOLAR cells , *PHONON scattering , *SOLIDS , *ADDITIVES - Abstract
Strong electron‐phonon coupling can hinder exciton transport and induce undesirable non‐radiative recombination, resulting in a shortened exciton diffusion distance and constrained exciton dissociation in organic solar cells (OSCs). Therefore, suppressing electron‐phonon coupling is crucially important for achieveing high‐performance OSCs. Here, we employ the solid additive to regulating electron‐phonon coupling in OSCs. The planar configuration of SA1 confers a significant advantage in suppressing lattice vibrations in the active layers, reducing the scattering of excitons by phonons. Consequently, a slow but sustained hole transfer process is identified in the SA1‐assisted film, indicating an enhancement in hole transfer efficiency. Prolonged exciton diffusion length and exciton lifetime are achieved in the blend film processed with SA1, attributed to a low non‐radiative recombination rate and low energetic disorder for charge carrier transport. As a result, a high efficiency of 20 % was achieved for ternary device with a remarkable short‐circuit current. This work highlights the important role of suppressing electron‐phonon coupling in improving the photovoltaic performance of OSCs. [ABSTRACT FROM AUTHOR]
- Published
- 2025
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22. Unveiling the Unusual Electron–Phonon Interaction and Quasi‐Particle Dynamics in type‐II Weyl Semimetal NbIrTe4.
- Author
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Sun, Kaiwen, Liu, Xiangqi, Wang, Chen, Lin, Xian, Suo, Peng, Guo, Yanfeng, and Ma, Guohong
- Subjects
NONLINEAR optics ,PHONONS ,ANISOTROPY ,PHOTOEXCITATION ,SEMIMETALS ,OPTOELECTRONIC devices ,POLARONS - Abstract
Layered ternary type‐II Weyl semimetals demonstrate promising applications in high‐performance and broadband optoelectronics, therefore it is crucial to gain insights into their photocarriers' dynamics. In this work, the probing polarization dependence of non‐equilibrium dynamics in NbIrTe4 is investigated by using transient reflectivity spectroscopy. Following photoexcitation at 3.18 eV, the dynamical response of 1.59 eV probe pulse exhibits a strong dependence on probe polarization. The relaxation comprises two components: a rapid recovery of ≈0.6 ps attributed to the electron–phonon scattering, and an anomalous slow recovery spanning hundreds of picoseconds attributed to the photoinduced quasi‐particle. The polarization dependence of rapid relaxation time τ is indicative of the in‐plane anisotropy of electron–phonon coupling in NbIrTe4. The slow relaxation modulated by a latest reported 16 cm−1 coherent phonon also shows strong probing polarization dependence, further revealing the anisotropic nature of electron–phonon coupling and the possibility of anisotropic lattice distortion, as well as photoinduced polaron, under ultrafast photoexcitation in NbIrTe4. The dynamical anisotropy in NbIrTe4 has provided valuable guidance for the application of NbIrTe4 in polarization‐sensitive nonlinear optics or optoelectronic devices and offers insights into the unique carrier transport as well as phonon transport properties of this newly established topological material. [ABSTRACT FROM AUTHOR]
- Published
- 2025
- Full Text
- View/download PDF
23. Colossal magnetoresistance from spin-polarized polarons in an Ising system.
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Ying-Fei Li, Been, Emily M., Balguri, Sudhaman, Chun-Jing Jia, Mahendru, Mira B., Zhi-Cheng Wang, Yi Cui, Su-Di Chen, Makoto Hashimoto, Dong-Hui Lu, Moritz, Brian, Zaanen, Jan, Tafti, Fazel, Devereaux, Thomas P., and Zhi-Xun Shen
- Subjects
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MAGNETIC transitions , *PHOTOELECTRON spectroscopy , *ELECTRON-phonon interactions , *CONDENSED matter , *DENSITY functional theory - Abstract
Recent experiments suggest a new paradigm toward novel colossal magnetoresistance (CMR) in a family of materials EuM2X2 (M = Cd, In, Zn; X = P, As), distinct from the traditional avenues involving Kondo-Ruderman-Kittel-Kasuya-Yosida crossovers, magnetic phase transitions with structural distortions, or topological phase transitions. Here, we use angle-resolved photoemission spectroscopy and density functional theory calculations to explore their origin, particularly focusing on EuCd2P2. While the low-energy spectral weight royally tracks that of the resistivity anomaly near the temperature with maximum magnetoresistance (TMR) as expected from transport-spectroscopy correspondence, the spectra are completely incoherent and strongly suppressed with no hint of a Landau quasiparticle. Using systematic material and temperature dependence investigation complemented by theory, we attribute this nonquasiparticle caricature to the strong presence of entangled magnetic and lattice interactions, a characteristic enabled by the p-f mixing. Given the known presence of ferromagnetic clusters, this naturally points to the origin of CMR being the scattering of spin-polarized polarons at the boundaries of ferromagnetic clusters. These results are not only illuminating to investigate the strong correlations and topology in EuCd2X2 family, but, in a broader view, exemplify how multiple cooperative interactions can give rise to extraordinary behaviors in condensed matter systems. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
24. Superconductivity in Alkali Metal-Deposited Monolayer BC: MBC (M = Na, K).
- Author
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Li, Ya-Ping, Yang, Liu, Liu, Hao-Dong, Shang, Shu-Ying, and Chen, Ying-Jie
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SUPERCONDUCTING transition temperature , *HIGH temperature superconductors , *ELECTRON-phonon interactions , *ELECTRONIC equipment , *SUPERCONDUCTORS - Abstract
In recent years, as two-dimensional (2D) materials have been widely used in electronic devices, searching for 2D high superconducting transition temperature ( T c ) superconductors has also attracted great attentions. In this work, based on first-principles calculations and Eliashberg equation, the electronic structure, electron-phonon coupling (EPC) and possible superconductivity of alkali metal-deposited monolayer BC: MBC (M = Na, K) are studied. The results show that MBC (M = Na, K) are metallic and potential superconductors. The calculated EPC constants of MBC (M = Na, K) are 0.97 and 1.48, respectively. The strong coupling of MBC (M = Na, K) mainly origins from the coupling between electrons with the in-plane vibration modes of C and B atoms. The T c of MBC (M = Na, K) are 34.1 K and 41.7 K, respectively, and the T c of NaBC can be increased to 45.6 K under 2% biaxial tensile strain, and the T c of KBC can be boosted to 53.8 K under 1% biaxial tensile strain. It is anticipated that the predicted monolayer MBC (M = Na, K) and its strained cases can be realized in future experiments. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. Exfoliation and optical properties of S = 1 triangular lattice antiferromagnet NiGa2S4
- Author
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Jazzmin Victorin, Aleksandar Razpopov, Tomoya Higo, Reynolds Dziobek-Garrett, Thomas J. Kempa, Satoru Nakatsuji, Roser Valentí, and Natalia Drichko
- Subjects
Two-dimensional magnetic materials ,Mott insulator ,Raman spectroscopy ,Reflectance ,Electron-phonon coupling ,Doping ,Medicine ,Science - Abstract
Abstract Two-dimensional (2D) van der Waals (vdW) materials have been an exciting area of research ever since scientists first isolated a single layer of graphene. Single layer magnetic materials can provide a pathway for vdW heterostructures with magnetic properties. While most of the magnetic vdW materials exhibit ordering transitions in the bulk, here we report a successful exfoliation of a triangular lattice S = 1 antiferromagnet NiGa $$_2$$ S $$_4$$ , which already demonstrates exotic magnetism in the bulk material. We establish the number of layers of the material by atomic force microscopy (AFM) and detail a careful characterization using Raman and optical spectroscopy to demonstrate how the optical, electronic, and structural properties of NiGa $$_2$$ S $$_4$$ change as a function of sample thickness. Optical measurements and electronic structure calculations of bulk versus monolayer NiGa $$_2$$ S $$_4$$ confirm the material to be a Mott insulator with an electronic gap of about 1.5 eV, which slightly increases for layers below 10 L. We conclude with a theoretical analysis of the possibility of doping monolayer NiGa $$_2$$ S $$_4$$ by proximity to a metal.
- Published
- 2024
- Full Text
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26. Hydrogen‐Doped c‐BN as a Promising Path to High‐Temperature Superconductivity Above 120 K at Ambient Pressure.
- Author
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Ding, Han‐Bin, Niu, Rui, Li, Shen‐Ao, Liu, Ying‐Ming, Chen, Xiao‐Jia, Lin, Hai‐Qing, and Zhong, Guo‐Hua
- Subjects
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PHASE transitions , *SUPERCONDUCTIVITY , *TRANSITION temperature , *HARD materials , *SUPERCONDUCTORS - Abstract
Finding high‐temperature superconductivity in light‐weight element containing compounds at atmosphere pressure is currently a research hotspot but has not been reached yet. Here it is proposed that hard or superhard materials can be promising candidates to possess the desirable high‐temperature superconductivity. By studying the electronic structures and superconducting properties of H and Li doped c‐BN within the framework of the first‐principles, it is demonstrated that the doped c‐BN are indeed good superconductors at ambient pressure after undergoing the phase transition from the insulating to metallic behavior, though holding different nature of metallization. Li doped c‐BN is predicted to exhibit the superconducting transition temperature of ≈58 K, while H doped c‐BN has stronger electron–phonon interaction and possesses a higher transition temperature of 122 K. These results and findings thus point out a new direction for exploring the ambient‐pressure higher‐temperature superconductivity in hard or superhard materials. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. Exfoliation and optical properties of S = 1 triangular lattice antiferromagnet NiGa2S4.
- Author
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Victorin, Jazzmin, Razpopov, Aleksandar, Higo, Tomoya, Dziobek-Garrett, Reynolds, Kempa, Thomas J., Nakatsuji, Satoru, Valentí, Roser, and Drichko, Natalia
- Abstract
Two-dimensional (2D) van der Waals (vdW) materials have been an exciting area of research ever since scientists first isolated a single layer of graphene. Single layer magnetic materials can provide a pathway for vdW heterostructures with magnetic properties. While most of the magnetic vdW materials exhibit ordering transitions in the bulk, here we report a successful exfoliation of a triangular lattice S = 1 antiferromagnet NiGa S , which already demonstrates exotic magnetism in the bulk material. We establish the number of layers of the material by atomic force microscopy (AFM) and detail a careful characterization using Raman and optical spectroscopy to demonstrate how the optical, electronic, and structural properties of NiGa S change as a function of sample thickness. Optical measurements and electronic structure calculations of bulk versus monolayer NiGa S confirm the material to be a Mott insulator with an electronic gap of about 1.5 eV, which slightly increases for layers below 10 L. We conclude with a theoretical analysis of the possibility of doping monolayer NiGa S by proximity to a metal. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. Superconductivity and Pronounced Electron‐Phonon Coupling in Rock‐Salt Al1−xO1−x and Ti1−xO1−x.
- Author
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Žguns, Pjotrs, Gedik, Nuh, Yildiz, Bilge, and Li, Ju
- Subjects
COUPLINGS (Gearing) ,DYNAMIC stability ,PARTIAL pressure ,SUPERCONDUCTIVITY ,CUPRATES - Abstract
The highest ambient‐pressure Tc among binary compounds is 40 K (MgB2). Higher Tc is achieved in high‐pressure hydrides or multielement cuprates. Alternatively, are explored superconducting properties of binary, metastable sub‐oxides, that may emerge under extremely low oxygen partial pressure. The emphasis is on the rock‐salt structure, which is known to promote superconductivity, and exploring AlO, ScO, TiO, and NbO. Dynamic lattice stability is achieved by introducing metal and oxygen vacancies in the fashion of Nb1−xO1−x‐type structure (x = ¼). The electron‐phonon (e‐ph) coupling is remarkably large in Al1−xO1−x and Ti1−xO1−x (λ ≈ 2 at x = ¼), with Tc ≈ 35 K according to the Allen–Dynes equation. Significantly, the coupling strength is comparable to that in high‐pressure hydrides, yet, in contrast to hydrides and MgB2, the coupling is largely driven by low frequency phonons. Sc1−xO1−x and Nb1−xO1−x show significantly smaller λ and Tc. Further, hydrogen intercalation to boost λ and Tc is investigated. Only Ti1−x(O1−xHx) and Nb1−x(O1−xHx) are dynamically stable upon intercalation, where H, respectively, decreases and increases Tc. The effect of H doping on electronic structure and Tc is discussed. Altogether, the study suggests that metal sub‐oxides are promising compounds to achieve strong e‐ph coupling at ambient pressure. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
29. High temperature superconductor Na2B2H stabilized by hydrogen intercalation under ambient pressure.
- Author
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Zhao, Wendi, Duan, Defang, Liu, Zhengtao, Huo, Zihao, Guo, Shumin, An, Decheng, Miao, Maosheng, and Cui, Tian
- Abstract
Hydrogenated metal borides have attracted much attention due to their potential high-temperature superconductivity. Here, we propose a new strategy for hydrogen intercalation tuning the stability and superconductivity of the boron honeycomb sublattice, and predict an unprecedented layered compound Na
2 B2 H, which hosts excellent superconductivity. Strikingly, the superconducting transition temperature (Tc ) of Na2 B2 H reaches 42 K at ambient pressure. The Tc value can be further increase to 63 K under 5% biaxial tensile strain. The excellent superconductivity originates from the strong electron-phonon coupling between the σ-bonding bands near the Fermi level and the B-B stretching optical E′ modes. The interstitial electron localization and crystal orbitals of the H-intercalated Na ion layer well match the boron honeycomb lattice and act as a chemical template to stabilize the B layer. Furthermore, the introduction of hydrogen tuned the Fermi level, and the coupling vibration of Na and H ions effectively enhanced the dynamic stability of the structure. Na2 B2 H represents a new family of layered high-temperature superconductors, and the strategy of stabilizing the honeycomb boron sublattice via chemical template hosts great potential for application to more layered compounds. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
30. Probing the Superconductivity Limit of Li‐Doped Graphene.
- Author
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Yang, Qiuping, Zhang, Huimin, Zhao, Jijun, and Jiang, Xue
- Subjects
- *
HIGH temperature superconductors , *SUPERCONDUCTIVITY , *GRAPHENE , *PHYSICS , *ATOMS - Abstract
The introduction of superconductivity in graphene systems is highly desirable from both fundamental physics and application perspectives. In this article, a superlattice strategy to develop a series of Li‐doped graphene is reported: deposition type‐I (Li2C6, Li2C8, LiC6, Li3C24, LiC12, LiC16, Li2C36, LiC24), intercalation type‐II (LiC4, Li2C12, LiC8, LiC12, LiC16), and coexisting deposition and intercalation type‐III (Li3C12). With increasing concentration of Li atoms, both metallicity, and electron–phonon coupling (EPC) has dramatically increased, which is favorable for the emergence of superconductivity in the screened Li–C compounds. Notably, graphene superlattice structures with intercalated Li2 atoms have higher stability, while Li1‐deposited graphene at the same concentration produces higher Tc. Among them, type‐I‐Li2C6, type‐I‐Li2C8, type‐II‐LiC4, and type‐III‐Li3C12 are phonon‐mediated superconductors with high transition temperatures (Tc) of 18, 12, 3.4, and 14 K, respectively. The EPC of type‐I‐Li2C6, type‐I‐Li2C8, and type‐III‐Li3C12 mainly arises from the coupling of the C‐2pz electron states with the low‐frequency (0–800 cm−1) deposition‐Lixy/Liz, and out‐of‐plane‐Cz vibrations. In contrast, the high‐frequency (800–1600 cm−1) vibration modes of in‐plane‐Cxy atoms are mainly responsible for the Tc of type‐II‐LiC4. The findings provide comprehensive insights into the superconductivity limit of Li‐doped graphene. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. High‐Throughput Study of Ambient‐Pressure High‐Temperature Superconductivity in Ductile Few‐Hydrogen Metal‐Bonded Perovskites.
- Author
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Liu, Shi‐ming, Shi, Jun‐jie, He, Yong, Tian, Chong, Zhu, Yao‐hui, Wang, Xinqiang, and Zhong, Hong‐xia
- Subjects
- *
SUPERCONDUCTIVITY , *SUPERCONDUCTORS , *PEROVSKITE , *CRITICAL temperature , *HIGH temperatures - Abstract
Several multi‐hydrogen hydrides have exhibited high critical temperature (Tc) superconductivity, but the requirement for ultrahigh pressures limits their applications. Here, high‐throughput calculations are utilized to investigate the superconductivity in few‐hydrogen metal‐bonded (FHMB) perovskites (PVSKs) AHM3 characterized with perfect ambient‐pressure stability. AHM3 is classified into two groups, d and sp superconductors, and provide three indicators that accurately describe AHM3 superconductivity. i) Tc of d superconductors is positively correlated with the number of unpaired d electrons from M atoms; ii) A suitably sized octahedral interstice of H atom is essential for sp superconductors; iii) The introduction of H will further improve the superconductivity, when the M atom has a lower electronegativity than H. ZnHCr3 and ZnHAl3, perfectly meeting the requirements aforementioned, exhibit the highest Tc of 30 and 80 K among the d and sp superconductors, respectively. The results are helpful for understanding the electron–phonon coupling (EPC) mechanism in few‐hydrogen metal‐bonded perovskites and facilitate realizations of ambient‐pressure high‐Tc superconductivity in hydrides. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Prediction of Room‐Temperature Superconductivity in Quasi‐Atomic H2‐Type Hydrides at High Pressure.
- Author
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Jiang, Qiwen, Duan, Defang, Song, Hao, Zhang, Zihan, Huo, Zihao, Jiang, Shuqing, Cui, Tian, and Yao, Yansun
- Subjects
- *
HIGH temperature superconductivity , *ELECTRONIC density of states , *SUPERCONDUCTIVITY , *FERMI level , *SUPERCONDUCTORS - Abstract
Achieving superconductivity at room temperature (RT) is a holy grail in physics. Recent discoveries on high‐Tc superconductivity in binary hydrides H3S and LaH10 at high pressure have directed the search for RT superconductors to compress hydrides with conventional electron–phonon mechanisms. Here, an exceptional family of superhydrides is predicated under high pressures, MH12 (M = Mg, Sc, Zr, Hf, Lu), all exhibiting RT superconductivity with calculated Tcs ranging from 313 to 398 K. In contrast to H3S and LaH10, the hydrogen sublattice in MH12 is arranged as quasi‐atomic H2 units. This unique configuration is closely associated with high Tc, attributed to the high electronic density of states derived from H2 antibonding states at the Fermi level and the strong electron–phonon coupling related to the bending vibration of H2 and H‐M‐H. Notably, MgH12 and ScH12 remain dynamically stable even at pressure below 100 GPa. The findings offer crucial insights into achieving RT superconductivity and pave the way for innovative directions in experimental research. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Strong Electron-Phonon Coupling Mediates Carrier Transport in BiFeO3.
- Author
-
Zeng, Yan, Chen, Hongyi, Wang, Qiuyu, Dong, Guohua, Wu, Yongyi, Qiu, Ruibin, Ma, Li, Zhang, Lili, Liu, Xiaoze, Li, Tao, Yu, Ting, Hu, Zhongqiang, Wang, Ti, Liu, Ming, Xu, Hongxing, Ou, Zhenwei, Peng, Bin, Chu, Weibin, Li, Zhe, and Wang, Cheng
- Subjects
BiFeO3 ,carrier transport ,electron-phonon coupling ,transient absorption microscopy - Abstract
The electron-phonon interaction is known as one of the major mechanisms determining electrical and thermal properties. In particular, it alters the carrier transport behaviors and sets fundamental limits to carrier mobility. Establishing how electrons interact with phonons and the resulting impact on the carrier transport property is significant for the development of high-efficiency electronic devices. Here, carrier transport behavior mediated by the electron-phonon coupling in BiFeO3 epitaxial thin films is directly observed. Acoustic phonons are generated by the inverse piezoelectric effect and coupled with photocarriers. Via the electron-phonon coupling, doughnut shape carrier distribution has been observed due to the coupling between hot carriers and phonons. The hot carrier quasi-ballistic transport length can reach 340 nm within 1 ps. The results suggest an effective approach to investigating the effects of electron-phonon interactions with temporal and spatial resolutions, which is of great importance for designing and improving electronic devices.
- Published
- 2023
34. Corrections of Electron–Phonon Coupling for Second‐Order Structural Phase Transitions.
- Author
-
Graml, Mario and Hingerl, Kurt
- Subjects
- *
PHASE transitions , *TRANSITION temperature , *LATENT heat , *CANONICAL ensemble , *UNIT cell - Abstract
Structural phase transitions are accompanied by a movement of one nucleus (or a few) in the crystallographic unit cell. If the nucleus movement is continuous, a second‐order phase transition without latent heat results, whereas an abrupt nucleus displacement indicates a first‐order phase transition with accompanying latent heat. Herein, a Hamiltonian including electron
– phonon coupling (EPC) as proposed by Kristoffel and Konsel is taken. Contrary to their treatment, both the kinetic energy of the nucleus and its position are treated. The interaction of the many‐electron system with the single nucleus is taken into account by the Born– Oppenheimer approximation and perturbative expressions for the free energies are derived. The nuclei corrections due to the entangled electrons are found to be minor, but highlight the importance of the symmetry breaking at low temperature. Furthermore the free energy for a canonical ensemble is computed, whereas Kristoffel and Konsel use a grand canonical ensemble, which allows to derive more stringent bounds on the free energy. For the zero‐order nucleus correction, the shift of the phase transition temperature by evaluating the free energy is deduced. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
35. Exploring the lead-free halide Cs2MGaBr6 (M = Li, Na) double perovskites for sustainable energy applications.
- Author
-
Sofi, Mudasir Younis, Khan, Mohd Shahid, Ali, Javid, and Khan, M. Ajmal
- Subjects
- *
BAND gaps , *CLEAN energy , *VISIBLE spectra , *LIGHT absorption , *COUPLING constants - Abstract
In recent years, there has been a growing emphasis on the exploration of sustainable and eco-friendly materials well-suited for advanced applications in the realms of thermoelectrics and optoelectronics. Lead-free halide double perovskites have emerged as a compelling class of materials in this context. Nevertheless, despite their potential utility, thorough investigations into their thermal transport characteristics remain limited. In this systematic investigation, we employ density functional theory (DFT) and post-DFT techniques to elucidate the essential stability parameters, transport properties, and carrier-lattice interactions of the metal halide-based Cs2MGaBr6 (X = Li, Ga) double perovskites. Our assessment of structural stability involves a meticulous description of stability index parameters and the optimization of pristine structures using the GGA-PBE potential. Additionally, we calibrate the electronic structure while taking spin–orbit coupling (SOC) effects into consideration by using a combination of GGA and GGA + mBJ potentials. Our findings reveal that the TB-mBJ derived band gaps of 1.82 eV and 1.78 eV for Cs2LiGaBr6 and Cs2NaGaBr6 reside within the visible spectrum, prompting further investigation into their thermal transport characteristics. Moreover, we analyze the phonon characteristics and vibrational modes, extending our investigation to examine the electron–phonon coupling strength. The scrutiny of the Fröhlich coupling constant and the Feynman polaron radius unveils a stronger electron–phonon coupling strength. In the domain of thermoelectrics, the significant figure of merit (zT) values of 1.08 and 1.04 for Cs2LiGaBr6 and Cs2NaGaBr6, respectively, emphasize the considerable potential of these materials for deployment in renewable energy applications. Furthermore, our computational investigation into optical properties, including the dielectric constant, optical absorption, and refractive index, demonstrates optimal performance within the visible spectrum. Specifically, elevated absorption coefficient values of 30 × 10 4 cm - 1 for Cs2LiGaBr6 and 40 × 10 4 cm - 1 for Cs2NaGaBr6 are noted across visible and infrared spectra, highlighting their promising potential in optoelectronic and solar cell technologies. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Electronic Structure Evolution in the Temperature Range of Metal–Insulator Transitions on Sn/Ge(111).
- Author
-
Nair, Maya N., Palacio, Irene, Ohtsubo, Yoshiyuki, Taleb‐Ibrahimi, Amina, Michel, Enrique G., Mascaraque, Arantzazu, and Tejeda, Antonio
- Subjects
- *
ELECTRONIC band structure , *ELECTRON configuration , *FERMI surfaces , *FERMI energy , *POLAR effects (Chemistry) , *METAL-insulator transitions - Abstract
One‐third of monolayer of Sn adatoms on a Ge(111) substrate forms a 2D triangular lattice with one unpaired electron per site. The system presents a metal–insulator transition when decreasing the temperature and it is known to exhibit strong electron–phonon coupling at 120–150 K. Herein, a study of the electronic band structure for α‐Sn/Ge(111) between 150 and 5 K is reported. Both the experimental Fermi surfaces and the energy dispersions along high symmetry directions as a function of the temperature are presented. At 5 K it is observed a weakly or low‐dispersing spectral feature, exhibiting an extended gap in the reciprocal space. This feature is derived from the topmost occupied band, which is metallic at high temperature and which develops a kink associated with the strong electron–phonon coupling. The spectral evolution is partially explained with an increase of the electron–phonon coupling when decreasing the temperature. The increase of the electron–phonon coupling at low temperatures gives light into the new physics of this 2D system. The bandwidth is progressively reduced when reducing the temperature, enhancing the electronic correlation effects, and triggering the Mott transition. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. Thermal oscillations and resonance in electron–phonon interaction process.
- Author
-
Awad, Emad, Dai, Weizhong, and Sobolev, Sergey
- Subjects
- *
RESONANT vibration , *ELECTRON-phonon interactions , *ELECTRON temperature , *THEORY of wave motion , *STOCHASTIC resonance , *ELECTRON paramagnetic resonance - Abstract
A recent theoretical study (Xu in Proc R Soc A Math Phys Eng Sci 477:20200913, 2021) has derived conditions on the coefficients of Jeffreys-type equation to predict thermal oscillations and resonance during phonon hydrodynamics in non-metallic solids. Thermal resonance, in which the temperature amplitude attains a maximum value (peak) in response to an external exciting frequency source, is a phenomenon pertinent to the presence of underdamped thermal oscillations and explicit finite speed for the thermal wave propagation. The present work investigates the occurrence condition for thermal resonance phenomenon during the electron–phonon interaction process in metals based on the hyperbolic two-temperature model. First, a sufficient condition for underdamped electron and lattice temperature oscillations is discussed by deriving a critical frequency (a material characteristic). It is shown that the critical frequency of thermal waves near room temperature, during electron–phonon interactions, may be on the order of terahertz ( 10 - 20 THz for Cu and Au, i.e., lying within the terahertz gap). It is found that whenever the natural frequency of metal temperature exceeds this frequency threshold, the temperature oscillations are of underdamped type. However, this condition is not necessary, since there is a small frequency domain, below this threshold, in which the underdamped thermal wave solution is available but not effective. Otherwise, the critical damping and the overdamping conditions of the temperature waves are determined numerically for a sample of pure metals. The thermal resonance conditions in both electron and lattice temperatures are investigated. The occurrence of resonance in both electron and lattice temperature is conditional on violating two distinct critical values of frequencies. When the natural frequency of the system becomes larger than these two critical values, an applied frequency equal to such a natural frequency can drive both electron and lattice temperatures to resonate together with different amplitudes and behaviors. However, the electron temperature resonates earlier than the lattice temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. Purity-dependent Lorenz number, electron hydrodynamics and electron-phonon coupling in WTe2.
- Author
-
Xie, Wei, Yang, Feng, Xu, Liangcai, Li, Xiaokang, Zhu, Zengwei, and Behnia, Kamran
- Abstract
We present a study of electrical and thermal transport in Weyl semimetal WTe
2 down to 0.3 K. The Wiedemann-Franz law holds below 2 K and a downward deviation starts above. The deviation is more pronounced in cleaner samples, as expected in the hydrodynamic picture of electronic transport, where a fraction of electron-electron collisions conserve momentum. Phonons are the dominant heat carriers and their mean-free-path does not display a Knudsen minimum. This is presumably a consequence of weak anharmonicity, as indicated by the temperature dependence of the specific heat. Frequent momentum exchange between phonons and electrons leads to quantum oscillations of the phononic thermal conductivity. Bloch-Grüneisen picture of electron-phonon scattering breaks down at low temperature when Umklapp ph-ph collisions cease to be a sink for electronic flow of momentum. Comparison with semi-metallic Sb shows that normal ph-ph collisions are amplified by anharmonicity. In both semimetals, at cryogenic temperature, e-ph collisions degrade the phononic flow of energy but not the electronic flow of momentum. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
39. Superconducting ternary hydrides: progress and challenges.
- Author
-
Zhao, Wendi, Huang, Xiaoli, Zhang, Zihan, Chen, Su, Du, Mingyang, Duan, Defang, and Cui, Tian
- Subjects
- *
HIGH temperature superconductors , *STRUCTURAL stability , *SUPERCONDUCTIVITY , *SUPERCONDUCTORS , *ELECTRONIC structure - Abstract
Since the discovery of the high-temperature superconductors H3S and LaH10 under high pressure, compressed hydrides have received extensive attention as promising candidates for room-temperature superconductors. As a result of current high-pressure theoretical and experimental studies, it is now known that almost all the binary hydrides with a high superconducting transition temperature (T c) require extremely high pressure to remain stable, hindering any practical application. In order to further lower the stable pressure and improve superconductivity, researchers have started exploring ternary hydrides and had many achievements in recent years. Here, we discuss recent progress in ternary hydrides, aiming to deepen the understanding of the key factors regulating the structural stability and superconductivity of ternary hydrides, such as structural motifs, bonding features, electronic structures, electron–phonon coupling, etc. Furthermore, the current issues and challenges of superconducting ternary hydrides are presented, together with the prospects and opportunities for future research. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Delocalizing Excitation for Highly‐Active Organic Photovoltaic Catalysts.
- Author
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Zhang, Zhenzhen, Xu, Chaoying, Sun, Qianlu, Zhu, Yufan, Yan, Wenlong, Cai, Guilong, Li, Yawen, Si, Wenqin, Lu, Xinhui, Xu, Weigao, Yang, Ye, and Lin, Yuze
- Subjects
- *
HETEROJUNCTIONS , *CHARGE carrier lifetime , *ELECTRON-phonon interactions , *HYDROGEN evolution reactions , *CATALYSTS , *PHOTOCATALYSTS , *CHARGE carriers - Abstract
Localized excitation in traditional organic photocatalysts typically prevents the generation and extraction of photo‐induced free charge carriers, limiting their activity enhancement under illumination. Here, we enhance delocalized photoexcitation of small molecular photovoltaic catalysts by weakening their electron‐phonon coupling via rational fluoro‐substitution. The optimized 2FBP‐4F catalyst we develop here exhibits a minimized Huang–Rhys factor of 0.35 in solution, high dielectric constant and strong crystallization in the solid state. As a result, the energy barrier for exciton dissociation is decreased, and more importantly, polarons are unusually observed in 2FBP‐4F nanoparticles (NPs). With the increased hole transfer efficiency and prolonged charge carrier lifetime highly related to enhanced exciton delocalization, the PM6 : 2FBP‐4F heterojunction NPs at varied concentration exhibit much higher optimized photocatalytic activity (207.6–561.8 mmol h−1 g−1) for hydrogen evolution than the control PM6 : BP‐4F and PM6 : 2FBP‐6F NPs, as well as other reported photocatalysts under simulated solar light (AM 1.5G, 100 mW cm−2). [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. A Giant Stokes Shift in Wide‐Band Red Phosphor [Ca0.33(Sr1‐xBax)0.67]7(SiO3)6Cl2: Eu2+.
- Author
-
Liu, Guihong, Wang, Yuhua, and Seto, Takatoshi
- Subjects
- *
STOKES shift , *ELECTRON-phonon interactions , *PHOSPHORS , *REDSHIFT , *ALKALINE earth metals , *BLUE light - Abstract
This paper investigates a wide‐band emitting red phosphor, an advancement that solves shortcomings including the re‐absorption of the yellow phosphor in the blue light area and a lack of red spectrum components which result in low color rendering and an uneven white light tone. An examination through femtosecond, Raman, and low‐temperature spectroscopy demonstrates why this phosphor has large Stokes shift (SS = 7.5×103 cm−1) and wide half‐peak width with a full‐width at half maximum (FWHM) of more than 170 nm. In these samples, it is importantly observed that larger lattice causes smaller electron–phonon coupling of Eu2+ activator, and meanwhile leads to less temperature dependency of emission peak width. The obtained sample, after cation replacement in (Ca1‐xSrx)7(SiO3)6Cl2: Eu2+ (CSSC: Eu2+), exhibits an emission spectrum covers the range from 450 to 800 nm while its excitation range is below 450 nm, in which not reabsorb the blue light. This matches well with blue phosphors that can also be excited by near‐ultraviolet chips. The fabricated white light‐emitting diode (w‐LED) device has an ideal color rendering index and correlated color temperature (Ra = 90.5, CCT = 3894 K), making it an excellent candidate material for white LED illumination. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. A Giant Stokes Shift in Wide‐Band Red Phosphor [Ca0.33(Sr1‐xBax)0.67]7(SiO3)6Cl2: Eu2+.
- Author
-
Liu, Guihong, Wang, Yuhua, and Seto, Takatoshi
- Subjects
STOKES shift ,ELECTRON-phonon interactions ,PHOSPHORS ,REDSHIFT ,ALKALINE earth metals ,BLUE light - Abstract
This paper investigates a wide‐band emitting red phosphor, an advancement that solves shortcomings including the re‐absorption of the yellow phosphor in the blue light area and a lack of red spectrum components which result in low color rendering and an uneven white light tone. An examination through femtosecond, Raman, and low‐temperature spectroscopy demonstrates why this phosphor has large Stokes shift (SS = 7.5×103 cm−1) and wide half‐peak width with a full‐width at half maximum (FWHM) of more than 170 nm. In these samples, it is importantly observed that larger lattice causes smaller electron–phonon coupling of Eu2+ activator, and meanwhile leads to less temperature dependency of emission peak width. The obtained sample, after cation replacement in (Ca1‐xSrx)7(SiO3)6Cl2: Eu2+ (CSSC: Eu2+), exhibits an emission spectrum covers the range from 450 to 800 nm while its excitation range is below 450 nm, in which not reabsorb the blue light. This matches well with blue phosphors that can also be excited by near‐ultraviolet chips. The fabricated white light‐emitting diode (w‐LED) device has an ideal color rendering index and correlated color temperature (Ra = 90.5, CCT = 3894 K), making it an excellent candidate material for white LED illumination. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. Superconductivity and Pronounced Electron‐Phonon Coupling in Rock‐Salt Al1−xO1−x and Ti1−xO1−x
- Author
-
Pjotrs Žguns, Nuh Gedik, Bilge Yildiz, and Ju Li
- Subjects
BCS superconductivity ,electron‐phonon coupling ,sub‐oxides ,Electric apparatus and materials. Electric circuits. Electric networks ,TK452-454.4 ,Physics ,QC1-999 - Abstract
Abstract The highest ambient‐pressure Tc among binary compounds is 40 K (MgB2). Higher Tc is achieved in high‐pressure hydrides or multielement cuprates. Alternatively, are explored superconducting properties of binary, metastable sub‐oxides, that may emerge under extremely low oxygen partial pressure. The emphasis is on the rock‐salt structure, which is known to promote superconductivity, and exploring AlO, ScO, TiO, and NbO. Dynamic lattice stability is achieved by introducing metal and oxygen vacancies in the fashion of Nb1−xO1−x‐type structure (x = ¼). The electron‐phonon (e‐ph) coupling is remarkably large in Al1−xO1−x and Ti1−xO1−x (λ ≈ 2 at x = ¼), with Tc ≈ 35 K according to the Allen–Dynes equation. Significantly, the coupling strength is comparable to that in high‐pressure hydrides, yet, in contrast to hydrides and MgB2, the coupling is largely driven by low frequency phonons. Sc1−xO1−x and Nb1−xO1−x show significantly smaller λ and Tc. Further, hydrogen intercalation to boost λ and Tc is investigated. Only Ti1−x(O1−xHx) and Nb1−x(O1−xHx) are dynamically stable upon intercalation, where H, respectively, decreases and increases Tc. The effect of H doping on electronic structure and Tc is discussed. Altogether, the study suggests that metal sub‐oxides are promising compounds to achieve strong e‐ph coupling at ambient pressure.
- Published
- 2024
- Full Text
- View/download PDF
44. Characterization of the Thermal Properties of Ir/Pt Bilayer Transition Edge Sensors
- Author
-
Zhang, J, Chang, CL, Fujikawa, B, Karapetrov, G, Kolomensky, Yu G, Kwok, W-K, Lisovenko, M, Novosad, V, Pearson, J, Singh, V, Wang, G, Welliver, B, Welp, U, and Yefremenko, VG
- Subjects
Transition edge sensor ,Electron-phonon coupling ,Iridium platinum bilayer ,Gold ,Mathematical Physics ,Classical Physics ,Condensed Matter Physics ,General Physics - Abstract
We are developing a low-Tc TES-based large-area and low-threshold detector targeting a variety of potential applications. The detector consists of a 50.8-mm-diameter Si wafer as the substrate and radiation absorber, a single Ir/Pt bilayer TES sensor in the center, and normal metal Au pads added to the TES to strengthen the TES–absorber thermal coupling. Tight TES–absorber thermal coupling improves detector sensitivity and response uniformity. Here, we report on the electron–phonon (e–ph) coupling strengths for the Ir/Pt bilayer and Au that are measured with our prototype detectors and TES devices. We found that a second weak thermal link besides the one due to e–ph coupling in Ir/Pt or Au was required to explain our data. With the effects of the second weak link accounted for, the extracted e–ph coupling constant Σ for Ir/Pt bilayer in the Tc range between 32 and 70 mK is 1.9×108WK-5m-3, and Σ’s for Au at 40 mK and 55 mK are 2.2×109WK-5m-3 and 3.2×109WK-5m-3, respectively.
- Published
- 2023
45. Ternary superconducting hydrides stabilized via Th and Ce elements at mild pressures
- Author
-
Qiwen Jiang, Zihan Zhang, Hao Song, Yanbin Ma, Yuanhui Sun, Maosheng Miao, Tian Cui, and Defang Duan
- Subjects
High pressure ,Hydrides ,Superconductivity ,Ab initio calculations ,Electron-phonon coupling ,Science (General) ,Q1-390 - Abstract
The discovery of covalent H3S and clathrate structure LaH10 with excellent superconducting critical temperatures at high pressures has facilitated a multitude of research on compressed hydrides. However, their superconducting pressures are too high (generally above 150 GPa), thereby hindering their application. In addition, making room-temperature superconductivity close to ambient pressure in hydrogen-based superconductors is challenging. In this work, we calculated the chemically “pre-compressed” Be-H by heavy metals Th and Ce to stabilize the superconducting phase near ambient pressure. An unprecedented ThBeH8 (CeBeH8) with a “fluorite-type” structure was predicted to be thermodynamically stable above 69 GPa (76 GPa), yielding a Tc of 113 K (28 K) decompressed to 7 GPa (13 GPa) by solving the anisotropic Migdal–Eliashberg equations. Be-H vibrations play a vital role in electron–phonon coupling and structural stability of these ternary hydrides. Our results will guide further experiments toward synthesizing ternary hydride superconductors at mild pressures.
- Published
- 2024
- Full Text
- View/download PDF
46. Structurally Flexible 2D Spacer for Suppressing the Electron–Phonon Coupling Induced Non-Radiative Decay in Perovskite Solar Cells
- Author
-
Ruikun Cao, Kexuan Sun, Chang Liu, Yuhong Mao, Wei Guo, Ping Ouyang, Yuanyuan Meng, Ruijia Tian, Lisha Xie, Xujie Lü, and Ziyi Ge
- Subjects
Electron–phonon coupling ,A-site cation engineering ,Non-radiative recombination ,Technology - Abstract
Highlights The soft 2D material reduces the coupling strength between carriers and longitudinal optical phonons, releasing the mechanical stress of lattice vibration. The power conversion efficiency of rigid devices and flexible devices reaches 25.5% and 23.4%, respectively.
- Published
- 2024
- Full Text
- View/download PDF
47. Open problems in transport physics of ultrahigh-thermal conductivity materials
- Author
-
Li, Xun and Shi, Li
- Published
- 2024
- Full Text
- View/download PDF
48. Optimizing Molecular Crystallinity and Suppressing Electron‐Phonon Coupling in Completely Non‐Fused Ring Electron Acceptors for Organic Solar Cells.
- Author
-
Dai, Tingting, Tang, Ailing, Meng, Yuhan, Dong, Chuanqi, Cong, Peiqing, Lu, Jiahao, Du, Jimin, Zhong, Yufei, and Zhou, Erjun
- Subjects
- *
ELECTRON-phonon interactions , *SOLAR cells , *ELECTRON donors , *ELECTROPHILES , *MOLECULAR structure , *OPEN-circuit voltage , *CRYSTALLINITY - Abstract
High open‐circuit voltage (Voc) organic solar cells (OSCs) have received increasing attention because of their promising application in tandem devices and indoor photovoltaics. However, the lack of a precise correlation between molecular structure and stacking behaviors of wide band gap electron acceptors has greatly limited its development. Here, we adopted an asymmetric halogenation strategy (AHS) and synthesized two completely non‐fused ring electron acceptors (NFREAs), HF‐BTA33 and HCl‐BTA33. The results show that AHS significantly enhances the molecular dipoles and suppresses electron‐phonon coupling, resulting in enhanced intramolecular/intermolecular interactions and decreased nonradiative decay. As a result, PTQ10 : HF‐BTA33 realizes a power conversion efficiency (PCE) of 11.42 % with a Voc of 1.232 V, higher than that of symmetric analogue F‐BTA33 (PCE=10.02 %, Voc=1.197 V). Notably, PTQ10 : HCl‐BTA33 achieves the highest PCE of 12.54 % with a Voc of 1.201 V due to the long‐range ordered π–π packing and enhanced surface electrostatic interactions thereby facilitating exciton dissociation and charge transport. This work not only proves that asymmetric halogenation of completely NFREAs is a simple and effective strategy for achieving both high PCE and Voc, but also provides deeper insights for the precise molecular design of low cost completely NFREAs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. Superhard and Superconducting Bilayer Borophene.
- Author
-
Zhong, Chengyong, Sun, Minglei, Altalhi, Tariq, and Yakobson, Boris I.
- Subjects
- *
METALLIC bonds , *SUPERCONDUCTIVITY , *CRITICAL temperature , *SUPERCONDUCTORS , *COVALENT bonds - Abstract
Two-dimensional superconductors, especially the covalent metals such as borophene, have received significant attention due to their new fundamental physics, as well as potential applications. Furthermore, the bilayer borophene has recently ignited interest due to its high stability and versatile properties. Here, the mechanical and superconducting properties of bilayer- δ 6 borophene are explored by means of first-principles computations and anisotropic Migdal–Eliashberg analytics. We find that the coexistence of strong covalent bonds and delocalized metallic bonds endows this structure with remarkable mechanical properties (maximum 2D-Young's modulus of ~570 N/m) and superconductivity with a critical temperature of ~20 K. Moreover, the superconducting critical temperature of this structure can be further boosted to ~46 K by applied strain, which is the highest value known among all borophenes or two-dimensional elemental materials. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Lattice Instability Induced Concerted Structural Distortion in Charged and van der Waals Layered GdTe3.
- Author
-
Dutta, Prabir, Chandra, Sushmita, Maria, Ivy, Debnath, Koyendrila, Rawat, Divya, Soni, Ajay, Waghmare, Umesh V., and Biswas, Kanishka
- Subjects
- *
PHONON scattering , *RARE earth metals , *CHARGE density waves , *ELECTRON-phonon interactions , *FERMI surfaces , *LATTICE dynamics - Abstract
Structural mosaic of rare-earth tri-tellurides (RTe3) inlaid with non-classical structural motifs like the 2D-polytelluride square nets has attracted immense attention owing to their enigmatic chemical bonding, unconventional structure, and harboring charge density wave (CDW) ground states. GdTe3, an archetypal RTe3, is a natural heterostructure of charged and van der Waals (vdW) layers, formed by intercalating vdW gap separated 2D square telluride nets between the charged double corrugated slabs of n[GdTe]+. Here, we have investigated the evolution of structural distortions along with the electrical and thermal transport properties of GdTe3 across its CDW transition through X-ray pair distribution function analysis, thermal conductivity measurements, Raman spectroscopy and first principles theoretical calculations. The results reveal that the unusual structure of GdTe3 engenders a large anisotropic lattice thermal conductivity by concomitantly hampering the phonon propagation along parallel to the spark plasma sintering (SPS) pressing direction via chemical bonding hierarchy while facilitating phonon propagation along perpendicular to the SPS pressing direction through the metallic Te sheets and phason channel. The low lattice thermal conductivity is attributed to the strong vibrational anharmonicity caused by CDW-induced concerted local lattice distortions of both Gd-Te slab and Te square net, and the robust electron-phonon coupling. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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