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Chen S, Wang Y, Bai F, Wu X, Wu X, Pakhomova A, Guo J, Huang X, Cui T. Superior Superconducting Properties Realized in Quaternary La-Y-Ce Hydrides at Moderate Pressures. J Am Chem Soc 2024; 146:14105-14113. [PMID: 38717019 DOI: 10.1021/jacs.4c02586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
The recent revolution in the superconductivity field stems from hydride superconductors. Multicomponent hydrides provide a crucial platform for tracking high-temperature superconductors. Besides high superconducting transition temperature (Tc), achieving both giant upper critical magnetic field [μ0Hc2(0)] and high critical current density [Jc(0)] is also key to the latent potential of the application for hydride superconductors. In this work, we have successfully synthesized quaternary La-Y-Ce hydrides with excellent properties under moderate pressure by using the concept of "entropy engineering." The obtained temperature dependence of the resistance provides evidence for the superconductivity of Fm3m-(La,Y,Ce)H10, with the maximum Tc ∼ 190 K (at 112 GPa). Notably, Fm3m-(La,Y,Ce)H10 boasts exceptional properties: μ0Hc2(0) reaching 292 T and Jc(0) surpassing 4.61 × 107 A/cm2. Compared with the binary LaH10/YH10, we find that the Fm3m structure in (La,Y,Ce)H10 can be stable at relatively low pressures (112 GPa). These results indicate that multicomponent hydrides can significantly enhance the superconducting properties and regulate stabilizing pressure through the application of "entropy engineering." This work stimulates the experimental exploration of multihydride superconductors and also provides a reference for the search of room-temperature superconductors in more diversified hydride materials in the future.
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Affiliation(s)
- Su Chen
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Yulong Wang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Fuquan Bai
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130021, P. R. China
| | - Xinzhao Wu
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130021, P. R. China
| | - Xinyue Wu
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Anna Pakhomova
- European Synchrotron Radiation Facility, ESRF, Grenoble 38043, Cedex 9, France
| | - Jianning Guo
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Xiaoli Huang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Tian Cui
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
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2
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Chen S, Qian Y, Huang X, Chen W, Guo J, Zhang K, Zhang J, Yuan H, Cui T. High-temperature superconductivity up to 223 K in the Al stabilized metastable hexagonal lanthanum superhydride. Natl Sci Rev 2024; 11:nwad107. [PMID: 38116091 PMCID: PMC10727841 DOI: 10.1093/nsr/nwad107] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 12/21/2023] Open
Abstract
As compressed hydrides constantly refresh the records of superconducting critical temperatures (Tc) in the vicinity of room temperature, this further reinforces the confidence to find more high-temperature superconducting hydrides. In this process, metastable phases of superhydrides offer enough possibilities to access superior superconducting properties. Here we report a metastable hexagonal lanthanum superhydride (P63/mmc-LaH10) stabilized at 146 GPa by introducing an appropriate proportion of Al, which exhibits high-temperature superconductivity with Tc ∼ 178 K, and this value is enhanced to a maximum Tc ∼ 223 K at 164 GPa. A huge upper critical magnetic field value Hc2(0) reaches 223 T at 146 GPa. The small volume expansion of P63/mmc-(La, Al) H10 compared with the binary LaH10 indicates the possible interstitial sites of Al atoms filling into the La-H lattice, instead of forming conventional ternary alloy-based superhydrides. This work provides a new strategy for metastable high-temperature superconductors through the multiple-element system.
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Affiliation(s)
- Su Chen
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
| | - Yingcai Qian
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei230031, China
| | - Xiaoli Huang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
| | - Wuhao Chen
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
| | - Jianning Guo
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
| | - Kexin Zhang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
| | - Jinglei Zhang
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei230031, China
| | - Huiqiu Yuan
- Center for Correlated Matter, College of Physics, Zhejiang University, Hangzhou 310058, China
| | - Tian Cui
- School of Physical Science and Technology, Ningbo University, Ningbo315211, China
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun130012, China
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3
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Wang PR, Yeh JW, Lee YH. The effect of critical coupling constants on superconductivity enhancement. Sci Rep 2023; 13:6475. [PMID: 37081112 PMCID: PMC10119179 DOI: 10.1038/s41598-023-33809-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 04/19/2023] [Indexed: 04/22/2023] Open
Abstract
In this study, we propose a phenomenological model to extend McMillan's results on a coupling strength equal to 2. We investigate possible strategies to enhance superconductivity by tuning the phonon frequency, carrier number, or pressure. In particular, we show that the critical coupling constants corresponding to the phonon frequency, carrier number, or pressure determine whether the variation of the critical temperature is positive or negative. These observations explain the contrasting behavior between weak and strong coupling superconductors and are consistent with experimental observations. We also demonstrate the dome observed in the carrier number effect and pressure effect. Additionally, these critical coupling constants systematically separate superconductivity into three regions: weak, intermediate, and strong coupling. We find that the enhancement strategies for weak and strong coupling regions are opposite, but both inevitably bring superconductivity into the intermediate coupling region. Finally, we propose general zigzag methods for intermediate coupling superconductors to further enhance the critical temperature.
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Affiliation(s)
- Peir-Ru Wang
- Department of Materials Science and Engineering, National Tsing Hua University, 30013, Hsinchu, Taiwan.
| | - Jien-Wei Yeh
- Department of Materials Science and Engineering, National Tsing Hua University, 30013, Hsinchu, Taiwan
| | - Yi-Hsien Lee
- Department of Materials Science and Engineering, National Tsing Hua University, 30013, Hsinchu, Taiwan
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4
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Talantsev EF. D-Wave Superconducting Gap Symmetry as a Model for Nb1−xMoxB2 (x = 0.25; 1.0) and WB2 Diborides. Symmetry (Basel) 2023. [DOI: 10.3390/sym15040812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
Abstract
Recently, Pei et al. (National Science Review2023, nwad034, 10.1093/nsr/nwad034) reported that ambient pressure β-MoB2 (space group: R3¯m) exhibits a phase transition to α-MoB2 (space group: P6/mmm) at pressure P~70 GPa, which is a high-temperature superconductor exhibiting Tc=32 K at P~110 GPa. Although α-MoB2 has the same crystalline structure as ambient-pressure MgB2 and the superconducting critical temperatures of α-MoB2 and MgB2 are very close, the first-principles calculations show that in α-MoB2, the states near the Fermi level, εF, are dominated by the d-electrons of Mo atoms, while in MgB2, the p-orbitals of boron atomic sheets dominantly contribute to the states near the εF. Recently, Hire et al. (Phys. Rev. B2022, 106, 174515) reported that the P6/mmm-phase can be stabilized at ambient pressure in Nb1−xMoxB2 solid solutions, and that these ternary alloys exhibit Tc~8 K. Additionally, Pei et al. (Sci. China-Phys. Mech. Astron. 2022, 65, 287412) showed that compressed WB2 exhibited Tc~15 K at P~121 GPa. Here, we aimed to reveal primary differences/similarities in superconducting state in MgB2 and in its recently discovered diboride counterparts, Nb1−xMoxB2 and highly-compressed WB2. By analyzing experimental data reported for P6/mmm-phases of Nb1−xMoxB2 (x = 0.25; 1.0) and highly compressed WB2, we showed that these three phases exhibit d-wave superconductivity. We deduced 2Δm(0)kBTc=4.1±0.2 for α-MoB2, 2Δm(0)kBTc=5.3±0.1 for Nb0.75Mo0.25B2, and 2Δm(0)kBTc=4.9±0.2 for WB2. We also found that Nb0.75Mo0.25B2 exhibited high strength of nonadiabaticity, which was quantified by the ratio of TθTF=3.5, whereas MgB2, α-MoB2, and WB2 exhibited TθTF~0.3, which is similar to the TθTF in pnictides, A15 alloys, Heusler alloys, Laves phase compounds, cuprates, and highly compressed hydrides.
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Talantsev EF. Quantifying Nonadiabaticity in Major Families of Superconductors. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 13:71. [PMID: 36615981 PMCID: PMC9824585 DOI: 10.3390/nano13010071] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/17/2022] [Accepted: 12/19/2022] [Indexed: 06/17/2023]
Abstract
The classical Bardeen−Cooper−Schrieffer and Eliashberg theories of the electron−phonon-mediated superconductivity are based on the Migdal theorem, which is an assumption that the energy of charge carriers, kBTF, significantly exceeds the phononic energy, ℏωD, of the crystalline lattice. This assumption, which is also known as adiabatic approximation, implies that the superconductor exhibits fast charge carriers and slow phonons. This picture is valid for pure metals and metallic alloys because these superconductors exhibit ℏωDkBTF<0.01. However, for n-type-doped semiconducting SrTiO3, this adiabatic approximation is not valid, because this material exhibits ℏωDkBTF≅50. There is a growing number of newly discovered superconductors which are also beyond the adiabatic approximation. Here, leaving aside pure theoretical aspects of nonadiabatic superconductors, we classified major classes of superconductors (including, elements, A-15 and Heusler alloys, Laves phases, intermetallics, noncentrosymmetric compounds, cuprates, pnictides, highly-compressed hydrides, and two-dimensional superconductors) by the strength of nonadiabaticity (which we defined by the ratio of the Debye temperature to the Fermi temperature, TθTF). We found that the majority of analyzed superconductors fall into the 0.025≤TθTF≤0.4 band. Based on the analysis, we proposed the classification scheme for the strength of nonadiabatic effects in superconductors and discussed how this classification is linked with other known empirical taxonomies in superconductivity.
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Affiliation(s)
- Evgueni F. Talantsev
- M. N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18 S. Kovalevskoy Str., 620108 Ekaterinburg, Russia; ; Tel.: +7-912-676-0374
- NANOTECH Centre, Ural Federal University, 19 Mira Str., 620002 Ekaterinburg, Russia
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6
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Semenok DV, Troyan IA, Sadakov AV, Zhou D, Galasso M, Kvashnin AG, Ivanova AG, Kruglov IA, Bykov AA, Terent'ev KY, Cherepakhin AV, Sobolevskiy OA, Pervakov KS, Seregin AY, Helm T, Förster T, Grockowiak AD, Tozer SW, Nakamoto Y, Shimizu K, Pudalov VM, Lyubutin IS, Oganov AR. Effect of Magnetic Impurities on Superconductivity in LaH 10. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2204038. [PMID: 35829689 DOI: 10.1002/adma.202204038] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/17/2022] [Indexed: 06/15/2023]
Abstract
Polyhydrides are a novel class of superconducting materials with extremely high critical parameters, which is very promising for sensor applications. On the other hand, a complete experimental study of the best so far known superconductor, lanthanum superhydride LaH10 , encounters a serious complication because of the large upper critical magnetic field HC2 (0), exceeding 120-160 T. It is found that partial replacement of La atoms by magnetic Nd atoms results in significant suppression of superconductivity in LaH10 : each at% of Nd causes a decrease in TC by 10-11 K, helping to control the critical parameters of this compound. Strong pulsed magnetic fields up to 68 T are used to study the Hall effect, magnetoresistance, and the magnetic phase diagram of ternary metal polyhydrides for the first time. Surprisingly, (La,Nd)H10 demonstrates completely linear HC2 (T) ∝ |T - TC |, which calls into question the applicability of the Werthamer-Helfand-Hohenberg model for polyhydrides. The suppression of superconductivity in LaH10 by magnetic Nd atoms and the robustness of TC with respect to nonmagnetic impurities (e.g., Y, Al, C) under Anderson's theorem gives new experimental evidence of the isotropic (s-wave) character of conventional electron-phonon pairing in lanthanum decahydride.
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Affiliation(s)
- Dmitrii V Semenok
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
| | - Ivan A Troyan
- Shubnikov Institute of Crystallography, Federal Scientific Research Center "Crystallography and Photonics", Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow, 119333, Russia
| | - Andrey V Sadakov
- V.L. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials, P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Di Zhou
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
| | - Michele Galasso
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
| | - Alexander G Kvashnin
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
| | - Anna G Ivanova
- Shubnikov Institute of Crystallography, Federal Scientific Research Center "Crystallography and Photonics", Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow, 119333, Russia
| | - Ivan A Kruglov
- Center for Fundamental and Applied Research, Dukhov Research Institute of Automatics (VNIIA), st. Sushchevskaya, 22, Moscow, 127055, Russia
- Laboratory of Computational Materials Discovery, Moscow Institute of Physics and Technology, 9 Institutsky Lane, Dolgoprudny, 141700, Russia
| | - Alexey A Bykov
- Crystal Physics Laboratory, NRC "Kurchatov Institute" PNPI, 1, mkr. Orlova roshcha, Gatchina, 188300, Russia
| | - Konstantin Y Terent'ev
- Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russia
| | - Alexander V Cherepakhin
- Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russia
| | - Oleg A Sobolevskiy
- V.L. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials, P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Kirill S Pervakov
- V.L. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials, P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Alexey Yu Seregin
- Shubnikov Institute of Crystallography, Federal Scientific Research Center "Crystallography and Photonics", Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow, 119333, Russia
- Synchrotron radiation source "KISI-Kurchatov", National Research Center "Kurchatov Institute", Moscow, 123182, Russia
| | - Toni Helm
- Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328, Dresden, Germany
| | - Tobias Förster
- Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328, Dresden, Germany
| | - Audrey D Grockowiak
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
- Brazilian Synchrotron Light Laboratory (LNLS/Sirius), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, 13083-100, Brazil
| | - Stanley W Tozer
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA
| | - Yuki Nakamoto
- KYOKUGEN, Graduate School of Engineering Science, Osaka University, Machikaneyamacho 1-3, Toyonaka, Osaka, 560-8531, Japan
| | - Katsuya Shimizu
- KYOKUGEN, Graduate School of Engineering Science, Osaka University, Machikaneyamacho 1-3, Toyonaka, Osaka, 560-8531, Japan
| | - Vladimir M Pudalov
- V.L. Ginzburg Center for High-Temperature Superconductivity and Quantum Materials, P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991, Russia
- HSE Tikhonov Moscow Institute of Electronics and Mathematics, National Research University Higher School of Economics, 20 Myasnitskaya ulitsa, Moscow, 101000, Russia
| | - Igor S Lyubutin
- Shubnikov Institute of Crystallography, Federal Scientific Research Center "Crystallography and Photonics", Russian Academy of Sciences, 59 Leninsky Prospekt, Moscow, 119333, Russia
| | - Artem R Oganov
- Materials Discovery Laboratory, Skolkovo Institute of Science and Technology, Bolshoy Boulevard, 30/1, Moscow, 121205, Russia
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7
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Minkov VS, Bud'ko SL, Balakirev FF, Prakapenka VB, Chariton S, Husband RJ, Liermann HP, Eremets MI. Magnetic field screening in hydrogen-rich high-temperature superconductors. Nat Commun 2022; 13:3194. [PMID: 35680889 PMCID: PMC9184750 DOI: 10.1038/s41467-022-30782-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 05/19/2022] [Indexed: 11/25/2022] Open
Abstract
In the last few years, the superconducting transition temperature, Tc, of hydrogen-rich compounds has increased dramatically, and is now approaching room temperature. However, the pressures at which these materials are stable exceed one million atmospheres and limit the number of available experimental studies. Superconductivity in hydrides has been primarily explored by electrical transport measurements, whereas magnetic properties, one of the most important characteristic of a superconductor, have not been satisfactory defined. Here, we develop SQUID magnetometry under extreme high-pressure conditions and report characteristic superconducting parameters for Im-3m-H3S and Fm-3m-LaH10-the representative members of two families of high-temperature superconducting hydrides. We determine a lower critical field Hc1 of ∼0.82 T and ∼0.55 T, and a London penetration depth λL of ∼20 nm and ∼30 nm in H3S and LaH10, respectively. The small values of λL indicate a high superfluid density in both hydrides. These compounds have the values of the Ginzburg-Landau parameter κ ∼12-20 and belong to the group of "moderate" type II superconductors, rather than being hard superconductors as would be intuitively expected from their high Tcs.
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Affiliation(s)
- V S Minkov
- Max Planck Institute for Chemistry, Hahn Meitner Weg 1, 55128, Mainz, Germany.
| | - S L Bud'ko
- Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, IA, 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA
| | - F F Balakirev
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - V B Prakapenka
- Center for Advanced Radiation Sources, University of Chicago, 5640 South Ellis Avenue, Chicago, IL, 60637, USA
| | - S Chariton
- Center for Advanced Radiation Sources, University of Chicago, 5640 South Ellis Avenue, Chicago, IL, 60637, USA
| | - R J Husband
- Photon Science, DESY, Notkestrasse 85, 22607, Hamburg, Germany
| | - H P Liermann
- Photon Science, DESY, Notkestrasse 85, 22607, Hamburg, Germany
| | - M I Eremets
- Max Planck Institute for Chemistry, Hahn Meitner Weg 1, 55128, Mainz, Germany.
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8
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Ma L, Wang K, Xie Y, Yang X, Wang Y, Zhou M, Liu H, Yu X, Zhao Y, Wang H, Liu G, Ma Y. High-Temperature Superconducting Phase in Clathrate Calcium Hydride CaH_{6} up to 215 K at a Pressure of 172 GPa. PHYSICAL REVIEW LETTERS 2022; 128:167001. [PMID: 35522494 DOI: 10.1103/physrevlett.128.167001] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 01/18/2022] [Accepted: 03/09/2022] [Indexed: 05/25/2023]
Abstract
The recent discovery of superconductive rare earth and actinide superhydrides has ushered in a new era of superconductivity research at high pressures. This distinct type of clathrate metal hydrides was first proposed for alkaline-earth-metal hydride CaH_{6} that, however, has long eluded experimental synthesis, impeding an understanding of pertinent physics. Here, we report successful synthesis of CaH_{6} and its measured superconducting critical temperature T_{c} of 215 K at 172 GPa, which is evidenced by a sharp drop of resistivity to zero and a characteristic decrease of T_{c} under a magnetic field up to 9 T. An estimate based on the Werthamer-Helfand-Hohenberg model gives a giant zero-temperature upper critical magnetic field of 203 T. These remarkable benchmark superconducting properties place CaH_{6} among the most outstanding high-T_{c} superhydrides, marking it as the hitherto only clathrate metal hydride outside the family of rare earth and actinide hydrides. This exceptional case raises great prospects of expanding the extraordinary class of high-T_{c} superhydrides to a broader variety of compounds that possess more diverse material features and physics characteristics.
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Affiliation(s)
- Liang Ma
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
- International Center of Future Science, Jilin University, Changchun 130012, China
| | - Kui Wang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
| | - Yu Xie
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
- Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Jilin University, Changchun 130012, China
| | - Xin Yang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
| | - Yingying Wang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
| | - Mi Zhou
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
| | - Hanyu Liu
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
- International Center of Future Science, Jilin University, Changchun 130012, China
- State Key Laboratory of Superhard Materials and Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, Changchun 130012, China
| | - Xiaohui Yu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yongsheng Zhao
- Deutsches Elektronen-Synchrotron DESY, Hamburg 22607, Germany
| | - Hongbo Wang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
| | - Guangtao Liu
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
| | - Yanming Ma
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- International Center of Computational Method and Software, College of Physics, Jilin University, Changchun 130012, China
- International Center of Future Science, Jilin University, Changchun 130012, China
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9
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High-temperature superconductivity on the verge of a structural instability in lanthanum superhydride. Nat Commun 2021; 12:6863. [PMID: 34824193 PMCID: PMC8617267 DOI: 10.1038/s41467-021-26706-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 10/14/2021] [Indexed: 11/28/2022] Open
Abstract
The possibility of high, room-temperature superconductivity was predicted for metallic hydrogen in the 1960s. However, metallization and superconductivity of hydrogen are yet to be unambiguously demonstrated and may require pressures as high as 5 million atmospheres. Rare earth based “superhydrides”, such as LaH10, can be considered as a close approximation of metallic hydrogen even though they form at moderately lower pressures. In superhydrides the predominance of H-H metallic bonds and high superconducting transition temperatures bear the hallmarks of metallic hydrogen. Still, experimental studies revealing the key factors controlling their superconductivity are scarce. Here, we report the pressure and magnetic field dependence of the superconducting order observed in LaH10. We determine that the high-symmetry high-temperature superconducting Fm-3m phase of LaH10 can be stabilized at substantially lower pressures than previously thought. We find a remarkable correlation between superconductivity and a structural instability indicating that lattice vibrations, responsible for the monoclinic structural distortions in LaH10, strongly affect the superconducting coupling. The experimental studies to understand the superconductivity of superhydrides remain scarce. Here, the authors report pressure and magnetic field dependence of superconductivity in LaH10, and indicate lattice vibrations strongly affect superconducting coupling.
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10
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Kong P, Minkov VS, Kuzovnikov MA, Drozdov AP, Besedin SP, Mozaffari S, Balicas L, Balakirev FF, Prakapenka VB, Chariton S, Knyazev DA, Greenberg E, Eremets MI. Superconductivity up to 243 K in the yttrium-hydrogen system under high pressure. Nat Commun 2021; 12:5075. [PMID: 34417471 PMCID: PMC8379216 DOI: 10.1038/s41467-021-25372-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 08/04/2021] [Indexed: 02/07/2023] Open
Abstract
The discovery of superconducting H3S with a critical temperature Tc∼200 K opened a door to room temperature superconductivity and stimulated further extensive studies of hydrogen-rich compounds stabilized by high pressure. Here, we report a comprehensive study of the yttrium-hydrogen system with the highest predicted Tcs among binary compounds and discuss the contradictions between different theoretical calculations and experimental data. We synthesized yttrium hydrides with the compositions of YH3, YH4, YH6 and YH9 in a diamond anvil cell and studied their crystal structures, electrical and magnetic transport properties, and isotopic effects. We found superconductivity in the Im-3m YH6 and P63/mmc YH9 phases with maximal Tcs of ∼220 K at 183 GPa and ∼243 K at 201 GPa, respectively. Fm-3m YH10 with the highest predicted Tc > 300 K was not observed in our experiments, and instead, YH9 was found to be the hydrogen-richest yttrium hydride in the studied pressure and temperature range up to record 410 GPa and 2250 K.
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Affiliation(s)
- Panpan Kong
- Max-Planck-Institut für Chemie, Mainz, Germany
| | | | - Mikhail A Kuzovnikov
- Institute of Solid State Physics Russian Academy of Sciences, Chernogolovka, Moscow District, Russia
| | | | | | - Shirin Mozaffari
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - Luis Balicas
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | | | - Vitali B Prakapenka
- Center for Advanced Radiation Sources, University of Chicago, Chicago, IL, USA
| | - Stella Chariton
- Center for Advanced Radiation Sources, University of Chicago, Chicago, IL, USA
| | - Dmitry A Knyazev
- Max-Planck-Institut für Mikrostrukturphysik, Halle (Saale), Germany
| | - Eran Greenberg
- Center for Advanced Radiation Sources, University of Chicago, Chicago, IL, USA
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11
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Classifying Charge Carrier Interaction in Highly Compressed Elements and Silane. MATERIALS 2021; 14:ma14154322. [PMID: 34361516 PMCID: PMC8347786 DOI: 10.3390/ma14154322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/24/2021] [Accepted: 07/30/2021] [Indexed: 11/17/2022]
Abstract
Since the pivotal experimental discovery of near-room-temperature superconductivity (NRTS) in highly compressed sulphur hydride by Drozdov et al. (Nature 2015, 525, 73-76), more than a dozen binary and ternary hydrogen-rich phases exhibiting superconducting transitions above 100 K have been discovered to date. There is a widely accepted theoretical point of view that the primary mechanism governing the emergence of superconductivity in hydrogen-rich phases is the electron-phonon pairing. However, the recent analysis of experimental temperature-dependent resistance, R(T), in H3S, LaHx, PrH9 and BaH12 (Talantsev, Supercond. Sci. Technol. 2021, 34, accepted) showed that these compounds exhibit the dominance of non-electron-phonon charge carrier interactions and, thus, it is unlikely that the electron-phonon pairing is the primary mechanism for the emergence of superconductivity in these materials. Here, we use the same approach to reveal the charge carrier interaction in highly compressed lithium, black phosphorous, sulfur, and silane. We found that all these superconductors exhibit the dominance of non-electron-phonon charge carrier interaction. This explains the failure to demonstrate the high-Tc values that are predicted for these materials by first-principles calculations which utilize the electron-phonon pairing as the mechanism for the emergence of their superconductivity. Our result implies that alternative pairing mechanisms (primarily the electron-electron retraction) should be tested within the first-principles calculations approach as possible mechanisms for the emergence of superconductivity in highly compressed lithium, black phosphorous, sulfur, and silane.
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12
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Abd-Shukor R. Coherence length versus transition temperature of hydride-based and room temperature superconductors. RESULTS IN PHYSICS 2021; 25:104219. [DOI: 10.1016/j.rinp.2021.104219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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13
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Talantsev EF. Comparison of highly-compressed C2/ m-SnH 12superhydride with conventional superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:285601. [PMID: 33908372 DOI: 10.1088/1361-648x/abfc18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 04/27/2021] [Indexed: 06/12/2023]
Abstract
Satterthwaite and Toepke (1970Phys. Rev. Lett.25741) predicted high-temperature superconductivity in hydrogen-rich metallic alloys, based on an idea that these compounds should exhibit high Debye frequency of the proton lattice, which boosts the superconducting transition temperature,Tc. The idea has got full confirmation more than four decades later when Drozdovet al(2015Nature52573) experimentally discovered near-room-temperature superconductivity in highly-compressed sulphur superhydride, H3S. To date, more than a dozen of high-temperature hydrogen-rich superconducting phases in Ba-H, Pr-H, P-H, Pt-H, Ce-H, Th-H, S-H, Y-H, La-H, and (La, Y)-H systems have been synthesized and, recently, Honget al(2021arXiv:2101.02846) reported on the discovery ofC2/m-SnH12phase with superconducting transition temperature ofTc∼ 70 K. Here we analyse the magnetoresistance data,R(T,B), ofC2/m-SnH12phase and report that this superhydride exhibits the ground state superconducting gap of Δ(0) = 9.2 ± 0.5 meV, the ratio of 2Δ(0)/kBTc= 3.3 ± 0.2, and 0.010 <Tc/TF< 0.014 (whereTFis the Fermi temperature) and, thus,C2/m-SnH12falls into unconventional superconductors band in the Uemura plot.
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Affiliation(s)
- E F Talantsev
- M.N. Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St., Ekaterinburg, 620108, Russia
- NANOTECH Centre, Ural Federal University, 19 Mira St., Ekaterinburg, 620002, Russia
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14
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Talantsev EF. Quantifying the Charge Carrier Interaction in Metallic Twisted Bilayer Graphene Superlattices. NANOMATERIALS 2021; 11:nano11051306. [PMID: 34063386 PMCID: PMC8156452 DOI: 10.3390/nano11051306] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 11/16/2022]
Abstract
The mechanism of charge carrier interaction in twisted bilayer graphene (TBG) remains an unresolved problem, where some researchers proposed the dominance of the electron-phonon interaction, while the others showed evidence for electron-electron or electron-magnon interactions. Here we propose to resolve this problem by generalizing the Bloch-Grüneisen equation and using it for the analysis of the temperature dependent resistivity in TBG. It is a well-established theoretical result that the Bloch-Grüneisen equation power-law exponent, p, exhibits exact integer values for certain mechanisms. For instance, p = 5 implies the electron-phonon interaction, p = 3 is associated with the electron-magnon interaction and p = 2 applies to the electron-electron interaction. Here we interpret the linear temperature-dependent resistance, widely observed in TBG, as p→1, which implies the quasielastic charge interaction with acoustic phonons. Thus, we fitted TBG resistance curves to the Bloch-Grüneisen equation, where we propose that p is a free-fitting parameter. We found that TBGs have a smoothly varied p-value (ranging from 1.4 to 4.4) depending on the Moiré superlattice constant, λ, or the charge carrier concentration, n. This implies that different mechanisms of the charge carrier interaction in TBG superlattices smoothly transition from one mechanism to another depending on, at least, λ and n. The proposed generalized Bloch-Grüneisen equation is applicable to a wide range of disciplines, including superconductivity and geology.
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Affiliation(s)
- Evgueni F. Talantsev
- M. N. Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St., 620108 Ekaterinburg, Russia; ; Tel.: +7-912-676-0374
- Nanotech Centre, Ural Federal University, 19 Mira St., 620002 Ekaterinburg, Russia
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15
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Snider E, Dasenbrock-Gammon N, McBride R, Wang X, Meyers N, Lawler KV, Zurek E, Salamat A, Dias RP. Synthesis of Yttrium Superhydride Superconductor with a Transition Temperature up to 262 K by Catalytic Hydrogenation at High Pressures. PHYSICAL REVIEW LETTERS 2021; 126:117003. [PMID: 33798352 DOI: 10.1103/physrevlett.126.117003] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/19/2021] [Indexed: 05/25/2023]
Abstract
The recent observation of room-temperature superconductivity will undoubtedly lead to a surge in the discovery of new, dense, hydrogen-rich materials. The rare earth metal superhydrides are predicted to have very high-T_{c} superconductivity that is tunable with changes in stoichiometry or doping. Here we report the synthesis of an yttrium superhydride that exhibits superconductivity at a critical temperature of 262 K at 182±8 GPa. A palladium thin film assists the synthesis by protecting the sputtered yttrium from oxidation and promoting subsequent hydrogenation. Phonon-mediated superconductivity is established by the observation of zero resistance, an isotope effect and the reduction of T_{c} under an external magnetic field. The upper critical magnetic field is 103 T at zero temperature.
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Affiliation(s)
- Elliot Snider
- Department of Mechanical Engineering, School of Engineering and Applied Sciences, University of Rochester, Rochester, New York 14627, USA
| | | | - Raymond McBride
- Department of Mechanical Engineering, School of Engineering and Applied Sciences, University of Rochester, Rochester, New York 14627, USA
| | - Xiaoyu Wang
- Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260, USA
| | - Noah Meyers
- Department of Mechanical Engineering, School of Engineering and Applied Sciences, University of Rochester, Rochester, New York 14627, USA
| | - Keith V Lawler
- Department of Chemistry & Biochemistry, University of Nevada Las Vegas, Las Vegas, Nevada 89154, USA
| | - Eva Zurek
- Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260, USA
| | - Ashkan Salamat
- Department of Physics & Astronomy, University of Nevada Las Vegas, Las Vegas, Nevada 89154, USA
| | - Ranga P Dias
- Department of Mechanical Engineering, School of Engineering and Applied Sciences, University of Rochester, Rochester, New York 14627, USA
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
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16
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Sun D, Naud MF, Nguyen DN, Betts JB, Singleton J, Balakirev FF. Composite pressure cell for pulsed magnets. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:023903. [PMID: 33648055 DOI: 10.1063/5.0025557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Extreme pressures and high magnetic fields can affect materials in profound and fascinating ways. However, large pressures and fields are often mutually incompatible; the rapidly changing fields provided by pulsed magnets induce eddy currents in the metallic components used in conventional pressure cells, causing serious heating, forces, and vibration. Here, we report a diamond-anvil-cell made mainly out of insulating composites that minimizes inductive heating while retaining sufficient strength to apply pressures of up to 8 GPa. Any residual metallic component is made of low-conductivity metals and patterned to reduce eddy currents. The simple design enables rapid sample or pressure changes, desired by pulsed-magnetic-field-facility users. The pressure cell has been used in pulsed magnetic fields of up to 65 T with no noticeable heating at cryogenic temperatures. Several measurement techniques are possible inside the cell at temperatures as low as 500 mK.
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Affiliation(s)
- Dan Sun
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - Martin F Naud
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - Doan N Nguyen
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - Jonathan B Betts
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - John Singleton
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - Fedor F Balakirev
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
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17
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Minkov VS, Prakapenka VB, Greenberg E, Eremets MI. A Boosted Critical Temperature of 166 K in Superconducting D
3
S Synthesized from Elemental Sulfur and Hydrogen. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202007091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Vasily S. Minkov
- Max-Planck Institut für Chemie Hahn-Meitner Weg 1 55128 Mainz Germany
| | - Vitali B. Prakapenka
- Center for Advanced Radiation Sources University of Chicago 5640 South Ellis Avenue 60637 Chicago IL USA
| | - Eran Greenberg
- Applied Physics Department Soreq Nuclear Research Center 81800 Yavne Israel
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18
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Minkov VS, Prakapenka VB, Greenberg E, Eremets MI. A Boosted Critical Temperature of 166 K in Superconducting D 3 S Synthesized from Elemental Sulfur and Hydrogen. Angew Chem Int Ed Engl 2020; 59:18970-18974. [PMID: 32633069 PMCID: PMC7589447 DOI: 10.1002/anie.202007091] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Indexed: 11/09/2022]
Abstract
The discovery of superconductivity in H3 S at 203 K marked an advance towards room-temperature superconductivity and demonstrated the potential of H-dominated compounds to possess a high critical temperature (Tc ). There have been numerous reports of the H-S system over the last five years, but important questions remain unanswered. It is crucial to verify whether the Tc was determined correctly for samples prepared from compressed H2 S, since they are inevitably contaminated with H-depleted byproducts. Here, we prepare stoichiometric H3 S by direct in situ synthesis from elemental S and excess H2 . The Im 3 ‾ m phase of D3 S samples exhibits a Tc significantly higher than previously reported values (ca. 150 K), reaching a maximum Tc of 166 K at 157 GPa. Furthermore, we confirm that the sharp decrease in Tc below 150 GPa is accompanied by continuous rhombohedral structural distortions and demonstrate that the Cccm phase is non-metallic, with molecular H2 units in the crystal structure.
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Affiliation(s)
- Vasily S. Minkov
- Max-Planck Institut für ChemieHahn-Meitner Weg 155128MainzGermany
| | - Vitali B. Prakapenka
- Center for Advanced Radiation SourcesUniversity of Chicago5640 South Ellis Avenue60637ChicagoILUSA
| | - Eran Greenberg
- Applied Physics DepartmentSoreq Nuclear Research Center81800YavneIsrael
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19
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Snider E, Dasenbrock-Gammon N, McBride R, Debessai M, Vindana H, Vencatasamy K, Lawler KV, Salamat A, Dias RP. Room-temperature superconductivity in a carbonaceous sulfur hydride. Nature 2020; 586:373-377. [DOI: 10.1038/s41586-020-2801-z] [Citation(s) in RCA: 379] [Impact Index Per Article: 94.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 09/08/2020] [Indexed: 11/09/2022]
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20
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Jeon H, Wang C, Yi S, Cho JH. Origin of enhanced chemical precompression in cerium hydride [Formula: see text]. Sci Rep 2020; 10:16878. [PMID: 33037271 PMCID: PMC7547066 DOI: 10.1038/s41598-020-73665-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/16/2020] [Indexed: 11/08/2022] Open
Abstract
The rare-earth metal hydrides with clathrate structures have been highly attractive because of their promising high-[Formula: see text] superconductivity at high pressure. Recently, cerium hydride [Formula: see text] composed of Ce-encapsulated clathrate H cages was synthesized at much lower pressures of 80-100 GPa, compared to other experimentally synthesized rare-earth hydrides such as [Formula: see text] and [Formula: see text]. Based on density-functional theory calculations, we find that the Ce 5p semicore and 4f/5d valence states strongly hybridize with the H 1s state, while a transfer of electrons occurs from Ce to H atoms. Further, we reveal that the delocalized nature of Ce 4f electrons plays an important role in the chemical precompression of clathrate H cages. Our findings not only suggest that the bonding nature between the Ce atoms and H cages is characterized as a mixture of ionic and covalent, but also have important implications for understanding the origin of enhanced chemical precompression that results in the lower pressures required for the synthesis of [Formula: see text].
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Affiliation(s)
- Hyunsoo Jeon
- Department of Physics, Research Institute for Natural Science, and Institute for High Pressure at Hanyang University, Hanyang University, 222 Wangsimni-ro, Seongdong-ku, Seoul, 04763 Republic of Korea
| | - Chongze Wang
- Department of Physics, Research Institute for Natural Science, and Institute for High Pressure at Hanyang University, Hanyang University, 222 Wangsimni-ro, Seongdong-ku, Seoul, 04763 Republic of Korea
| | - Seho Yi
- Department of Physics, Research Institute for Natural Science, and Institute for High Pressure at Hanyang University, Hanyang University, 222 Wangsimni-ro, Seongdong-ku, Seoul, 04763 Republic of Korea
| | - Jun-Hyung Cho
- Department of Physics, Research Institute for Natural Science, and Institute for High Pressure at Hanyang University, Hanyang University, 222 Wangsimni-ro, Seongdong-ku, Seoul, 04763 Republic of Korea
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21
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Classifying Induced Superconductivity in Atomically Thin Dirac-Cone Materials. CONDENSED MATTER 2019. [DOI: 10.3390/condmat4030083] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recently, Kayyalha et al. (Phys. Rev. Lett., 2019, 122, 047003) reported on the anomalous enhancement of the self-field critical currents (Ic (sf, T)) at low temperatures in Nb/BiSbTeSe2-nanoribbon/Nb Josephson junctions. The enhancement was attributed to the low-energy Andreev-bound states arising from the winding of the electronic wave function around the circumference of the topological insulator BiSbTeSe2 nanoribbon. It should be noted that identical enhancement in Ic (sf, T) and in the upper critical field (Bc2 (T)) in approximately the same reduced temperatures, were reported by several research groups in atomically thin junctions based on a variety of Dirac-cone materials (DCM) earlier. The analysis shows that in all these S/DCM/S systems, the enhancement is due to a new superconducting band opening. Taking into account that several intrinsic superconductors also exhibit the effect of new superconducting band(s) opening when sample thickness becomes thinner than the out-of-plane coherence length (c (0)), we reaffirm our previous proposal that there is a new phenomenon of additional superconducting band(s) opening in atomically thin films.
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