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First-principles calculations on structural stability and electronic properties of nitrogen-doped lutetium hydrides under pressure

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Physical Review Research 2023年第4期5卷 043238-043238页

作者： Xiaokuan Hao Xudong Wei Hanyu Liu Xiaoxu Song Rongxin Sun Guoying Gao Yongjun Tian Center for High Pressure Science (CHiPS) State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao Hebei 066004 China Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University Changchun 130012 China Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education) International Center of Future Science Jilin University Changchun 130012 China

Since the discovery of superconductivity, the realization of room-temperature superconductivity has been the long dream of mankind. Recently, it has been reported that nitrogen-doped lutetium hydride has room-temperature superconductivity at near-ambient conditions. However, there is no solid evidence of such tantalizing superconductivity in nitrogen-doped lutetium hydride synthesized by follow-up experiments. The compositions and crystal structures of the nitrogen-doped lutetium hydride are still unclear. Therefore, we here systematically study the structural stability and electronic properties of Fm3¯m LuH3 and N-doped Fm3¯m LuH3, such as 1, 2, 3, 4, and 8% N, by first-principles calculations. Our further electronic properties calculations show that all the simulated Lu-N-H ternary compounds are metallic, except for a semiconducting phase of Lu4H11N (LuH2.75N0.25). Remarkably, the contribution of the H atoms to the electronic density of states at the Fermi level could be tuned by the increasing N concentration. Electron-phonon coupling calculations also show that both Fm3¯m LuH3 and Pm3¯m Lu4H11N are superconducting with critical temperature Tc's of 23 and 32 K at 24 and 60 GPa, respectively. Our current results suggest that LuH3 and N-doped LuH3 could be potential superconductors only at high pressure, while the estimated Tc values are much lower than room temperature.

关键词： Density of states First-principles calculations Superconductivity Crystal structures

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Electronic correlations influence on the anomalous constitutive law between the structure and spectra of hydrogen bonds

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Physical Review Research 2024年第3期6卷 L032019-L032019页

作者： Rui Liu Xinrui Yang Famin Yu Depeng Zhang Lu Wang Ruhong Zhou Zhigang Wang Key Laboratory of Material Simulation Methods & Software of Ministry of Education College of Physics Institute of Atomic and Molecular Physics Normal School Institute of Theoretical Chemistry College of Chemistry Institute of Quantitative Biology College of Life Sciences Shanghai Institute for Advanced Study Department of Chemistry

Classical constitutive law between the structure and spectra has long been established in most physical processes and behaviors. Despite the emerging consensus, whether this law applies to microscopic systems adhering to quantum mechanics remains a fundamental and open question, due to limitations in even the most state-of-the-art experimental techniques. Here, we report an anomalous constitutive law of hydrogen bonds (X-H···Y) using a benchmark ab initio method. Notably, a donor X-H bond shortening occurred simultaneously with an unexpected redshift and enhanced intensity in IR spectra. The reason for donor X-H bond shortening is attributed to both the slowly increasing attractive force from the acceptor Y atom and the increasing short-range repulsive forces from other protons attached to the approaching acceptor Y atom. Furthermore, neither eliminating vibrational mixing nor introducing various physical effects make vibrational spectra respond to X-H bond shortening. Other structural-characterization NMR spectra provide robust evidence for this anomalous law. This anomalous law is ascribed to the interplay of electronic correlations. Our Letter thus inspires a reassessment of paradigms, which broadens the scope of microscopic behavior for finer control.

关键词： Hydrogen bonds Interatomic & molecular potentials Long-range interactions Potential energy surfaces Van der Waals interaction Molecules Electronic structure First-principles calculations

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High-throughput discovery of robust room-temperature superconductors among complex ternary clathrate hydrides

arXiv

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arXiv 2024年

作者： Ma, Tiancheng An, Decheng Zhang, Zihan Wu, Shuting Cui, Tian Duan, Defang Key Laboratory of Material Simulation Methods & Software Ministry of Education State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun130012 China Institute of High Pressure Physics School of Physical Science and Technology Ningbo University Ningbo315211 China

After the decade-long exhaustive study of binary high-Tc superconducting hydrides, the frontier of this stimulating research field has recently shifted to ternary hydrides with much expanded conformational space in search of coveted room-temperature superconductors. This task, however, presents a formidable challenge due to enormous demands on computational resources. Here, we devise an efficient high-throughput approach using keen material insights and a self-built database to screen for robust ternary hydrides in clathrate structures, which were proven to host highest Tc in binary hydrides, and to estimate Tc by a reliable empirical formula. This approach has made it possible to uncover a diverse set of complex multiple-hydrogen-cage ternary hydrides hosting near or above room-temperature Tc, which are beyond the reach of prevailing structure search methods. This study establishes a distinct paradigm that opens a fresh avenue to enable and accelerate the discovery of promising room-temperature superconductors among unprecedented complex clathrate hydrides. Copyright © 2024, The Authors. All rights reserved.

关键词： High temperature superconductors

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Prediction of High- Tc Phonon-Mediated Superconductivity with Strong Ising Spin-Orbit Coupling in Monolayer WNO

SSRN

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SSRN 2024年

作者： Liu, Zhengtao Zhang, Zihan Ma, Tiancheng Dong, Guiyan Cai, Jialiang Cui, Tian Duan, Defang Key Laboratory of Material Simulation Methods & Software Ministry of Education State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun130012 China Institute of High Pressure Physics School of Physical Science and Technology Ningbo University Ningbo315211 China

The Ising superconductor, due to its unique upper critical magnetic field, has become one of the most prominent subjects in the field of two-dimensional materials in recent years. Currently, the researches on Type I Ising superconductors mainly focus on transition metal chalcogenides (TMDs), however, the limited superconducting transition temperature (Tc) restricts their practical application. In addition to TMDs, Janus materials with central inversion symmetry breaking are also promising candidates for prossessing strong Ising spin orbital couple (SOC). Here, through high-throughput calculations of T-phase and H-phase Janus material transition metal nitrogen oxides (TMNOs), we obtain a potential high-Tc superconductor H-WNO. By solving the anisotropic Eliasberg equation, its Tc is predicted to be 46 K with strong electron phonon coupling of 1.71. Further calculations show that its Ising SOC is much stronger than Rashba SOC, and its average spin-orbit splitting energy at the Fermi level is comparable to that of the well-known Ising superconductor NbSe2, indicating that WNO is a potential excellent Ising superconductor. This is the first time that a Janus superconductor with high-Tc and strong Ising SOC was predicted. Our work opens up a new field to searching for high-Tc Ising superconductors. © 2024, The Authors. All rights reserved.

关键词： Spin orbit coupling

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Structures and Superconductivity of Hydrogen and Hydrides under Extreme Pressure

arXiv

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arXiv 2024年

作者： Zhang, Zihan Zhao, Wendi Duan, Defang Cui, Tian State Key Laboratory of Superhard Materials Key Laboratory of Material Simulation Methods & Software of Ministry of Education College of Physics Jilin University Changchun130012 China Institute of High Pressure Physics School of Physical Science and Technology Ningbo University Ningbo315211 China

Metallic hydrogen, existing in remarkably extreme environments, was predicted to exhibit long-sought room-temperature superconductivity. Although the superconductivity of metallic hydrogen has not been confirmed experimentally, superconductivity of hydrogen in hydrides was recently discovered with remarkably high critical temperature as theoretically predicted. In recent years, theoretical simulations have become a new paradigm for material science, especially exploration of material at extreme pressure. As the typical high-pressure material, metallic hydrogen has been providing a fertile playground for advanced simulations for long time. simulations not only provide the substitute of experiments for hydrogen at high-pressure, but also encouraged the discovery of almost all the experimentally discovered superconducting hydrides with the record high superconducting transition temperature. This work reviews recent progress in hydrogen and hydrides under extreme pressure, focusing on phase diagram, structures and the long-sought goal of high-temperature superconductivity. In the end, we highlight structural features of hydrides for realization of hydrogen-driven superconducting hydrides near ambient pressure. Copyright © 2024, The Authors. All rights reserved.

关键词： Hydrides

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Zeeman spin splittings with persistent spin textures in antiferromagnetic semiconductors

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Physical Review B 2023年第12期108卷 125108-125108页

作者： Xinran Liu Hong Jian Zhao Laurent Bellaiche Yanming Ma Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University Changchun 130012 China Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education) College of Physics Jilin University Changchun 130012 China International Center of Future Science Jilin University Changchun 130012 China Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun 130012 China

Realizing sizable Zeeman spin splittings (ZSSs) with persistent spin textures (PSTs) in semiconductors is promising for the design of high-performance spintronic devices. The ZSSs of this kind have long been known in ferromagnetic semiconductors, while whether antiferromagnetic semiconductors—much more plenteous than ferromagnetic semiconductors—can host an analogous effect remains elusive. Here, we show that such ZSSs can occur in antiferromagnetic semiconductors. By symmetry analysis, we find 12 magnetic point groups that can host ZSSs and PSTs, providing theoretical guidelines for screening the corresponding antiferromagnets. Our first-principles calculations further confirm CaTcO3 as an antiferromagnetic semiconductor showcasing ZSSs that are sizable (tens of meV), possibly controllable by a magnetic field, and accompanied with PSTs. Our work thus may open a route towards the application of antiferromagnetic semiconductors in spintronics.

关键词： Dresselhaus coupling Magnetoelectric effect Rashba coupling Zeeman effect Antiferromagnets Multiferroics Perovskites First-principles calculations

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Prominent stress-driven anomalies in superconductivity of yttrium hexahydride

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Physical Review B 2024年第6期109卷 064513-064513页

作者： Han Liu Chang Liu Yanming Ma Changfeng Chen Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University Changchun 130012 China Department of Physics and Astronomy University of Nevada Las Vegas Nevada 89154 USA State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun 130012 China International Center of Future Science Jilin University Changchun 130012 China

Yttrium hexahydride is a top superconducting superhydride, but its measured Tc data are widely scattered and well below theoretical predictions. These prominent anomalies remain unresolved despite major efforts, impeding the understanding of this distinct class of superb superconductors. Here, we show that nonhydrostatic stresses, which are omnipresent in high-pressure experiments but omitted in prior theoretical studies, cause large deviations of Tc from hydrostatic values, accounting for the strong scattering of experimental data and, joint with an anharmonic correction, reconciling the diverging theoretical and experimental Tc results. Analysis of stress-induced phonon and charge responses unveils the underlying microscopic mechanisms. These findings offer a viable solution to the notable superconductivity anomalies in YH6, and the insights have broad implications for other superconducting superhydrides and, more generally, superconductors under extreme compression.

关键词： First-principles calculations Superconductivity High-temperature superconductors

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Monolayer ThSi2N4: An indirect-gap semiconductor with ultra-high carrier mobility

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Physical Review B 2023年第20期108卷 205427-205427页

作者： Cheng Lu Chuyan Cui Jingning Zuo Hongxia Zhong Shi He Wei Dai Xin Zhong School of Mathematics and Physics China University of Geosciences (Wuhan) Wuhan 430074 China School of Mathematics and Physics Jingchu University of Technology Jingmen 448000 China Key Laboratory of Materials Simulation Methods & Software of Ministry of Education College of Physics Jilin University Changchun 130012 China

The recently synthesized MoSi2N4 monolayer [Science 369, 670 (2020)] exhibit outstanding environmental stability, moderate band gap, and excellent mechanical properties, which opens up a new avenue for the explorations of two-dimensional (2D) MA2Z4 materials. Inspired by this finding, we perform comprehensive structural predictions of MSi2N4 monolayers with lanthanide and actinide metals at the M site. Using the CALYPSO structural search method and first-principles calculations, we identify seven MSi2N4 monolayers with robust ambient stabilities, four of which are metals (M = Tm, Lu, Pa, Np) and three are semiconductors (M = Ce, Th, U). Of particular interest is the ThSi2N4 monolayer, which is an indirect-gap semiconductor with ultra-high electron mobility of 14384 cm2V−1s−1. Our results enrich the 2D MA2Z4 family and offer insights into the design and synthesis of novel multifunctional materials.

关键词： Electrical properties 2-dimensional systems Crystal structures First-principles calculations

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Stoichiometric Ternary Superhydride LaBeH8 as a New Template for High-Temperature Superconductivity at 110 K under 80 GPa

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Physical Review Letters 2023年第26期130卷 266001-266001页

作者： Yinggang Song Jingkai Bi Yuki Nakamoto Katsuya Shimizu Hanyu Liu Bo Zou Guangtao Liu Hongbo Wang Yanming Ma Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University Changchun 130012 China Center for Quantum Science and Technology under Extreme Conditions Osaka University Toyonaka Osaka 560-8531 Japan State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun 130012 China International Center of Future Science Jilin University Changchun 130012 China

The search for high-temperature superconducting superhydrides has recently moved into a new phase by going beyond extensively probed binary compounds and focusing on ternary ones with vastly expanded material types and configurations for property optimization. Theoretical and experimental works have revealed promising ternary compounds that superconduct at or above room temperature, but it remains a pressing challenge to synthesize stoichiometric ternary compounds with a well-resolved crystal structure that can host high-temperature superconductivity at submegabar pressures. Here, we report on the successful synthesis of ternary LaBeH8 obtained via compression in a diamond anvil cell under 110–130 GPa. X-ray diffraction unveils a rocksalt-like structure composing La and BeH8 units in the lattice. Transport measurements determined superconductivity with critical temperature Tc up to 110 K at 80 GPa, as evidenced by a sharp drop of resistivity to zero and a characteristic shift of Tc driven by a magnetic field. Our experiment establishes the first superconductive ternary compound with a resolved crystal structure. These findings raise the prospects of rational development of the class of high-Tc superhydrides among ternary compounds, opening greatly expanded and more diverse structural space for exploration and discovery of superhydrides with enhanced high-Tc superconductivity.

关键词： Pressure effects Superconducting phase transition High-temperature superconductors Hydrides Unconventional superconductors Crystal structures Pressure techniques Resistivity measurements X-ray diffraction

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Prediction of fully metallic σ-bonded boron framework induced high superconductivity above 100 K in thermodynamically stable Sr2B5 at 40 GPa

arXiv

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arXiv 2023年

作者： Yang, Xin Zhao, Wenbo Ma, Liang Lu, Wencheng Zhong, Xin Xie, Yu Liu, Hanyu Ma, Yanming Key Laboratory of Material Simulation Methods & Software Ministry of Education College of Physics Jilin University Changchun130012 China State Key Laboratory for Superhard Materials College of Physics Jilin University Changchun130012 China International Center of Future Science Jilin University Changchun130012 China Key Laboratory of Physics and Technology for Advanced Batteries Ministry of Education College of Physics Jilin University Changchun130012 China

Metal borides have been considered as potential high-temperature superconductors since the discovery of record-holding 39 K superconductivity in bulk MgB2. In this work, we identified a superconducting yet thermodynamically stable F(Equation presented)3m Sr2B5 at 40 GPa with a unique covalent sp3-hybridized boron framework through extensive first-principles structure searches. Remarkably, solving the anisotropic Migdal-Eliashberg equations resulted in a high superconducting critical temperature (Tc) around 100 K, exceeding the boiling point (77 K) of liquid nitrogen. Our in-depth analysis revealed that the high-temperature superconductivity mainly originates from the strong coupling between the metalized σ-bonded electronic bands and E phonon modes of boron atoms. Moreover, anharmonic phonon simulations suggest that F(Equation presented)3m Sr2B5 might be recovered to ambient pressure. Our current findings provide a prototype structure with a full σ-bonded boron framework for the design of high-Tc superconducting borides that may expand to a broader variety of lightweight compounds. © 2023, CC BY.

关键词： High temperature superconductors

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