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Majumdar, Arnab
Publications (2 of 2) Show all publications
Abdel-Hafiez, M., Thiyagarajan, R., Majumdar, A., Ahuja, R., Luo, W., Vasiliev, A. N., . . . Kulik, L. ,. (2019). Pressure-induced reentrant transition in NbS3 phases: Combined Raman scattering and x-ray diffraction study. Physical Review B, 99(23), Article ID 235126.
Open this publication in new window or tab >>Pressure-induced reentrant transition in NbS3 phases: Combined Raman scattering and x-ray diffraction study
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2019 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 99, no 23, article id 235126Article in journal (Refereed) Published
Abstract [en]

We report the evolution of charge density wave states under pressure for two NbS3 phases: triclinic (phase I) and monoclinic (phase II) at room temperature. Raman and x-ray diffraction (XRD) techniques are applied. The x-ray studies on the monoclinic phase under pressure show a compression of the lattice at different rates below and above similar to 7 GPa but without a change in space group symmetry. The Raman spectra of the two phases evolve similarly with pressure; all peaks almost disappear in the similar to 6-8 GPa range, indicating a transition from an insulating to a metallic state, and peaks at new positions appear above 8 GPa. The results suggest suppression of the ambient charge-density waves and their subsequent recovery with new orderings above 8 GPa.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2019
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-390211 (URN)10.1103/PhysRevB.99.235126 (DOI)000471983200001 ()
Available from: 2019-08-09 Created: 2019-08-09 Last updated: 2019-08-09Bibliographically approved
Ji, C., Li, B., Liu, W., Smith, J. S., Majumdar, A., Luo, W., . . . Mao, H.-K. (2019). Ultrahigh-pressure isostructural electronic transitions in hydrogen. Nature, 573(7775), 558-562
Open this publication in new window or tab >>Ultrahigh-pressure isostructural electronic transitions in hydrogen
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2019 (English)In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 573, no 7775, p. 558-562Article in journal (Refereed) Published
Abstract [en]

High-pressure transitions are thought to modify hydrogen molecules to a molecular metallic solid and finally to an atomic metal(1), which is predicted to have exotic physical properties and the topology of a two-component (electron and proton) superconducting superfluid condensate(2,3). Therefore, understanding such transitions remains an important objective in condensed matter physics(4,5). However, measurements of the crystal structure of solid hydrogen, which provides crucial information about the metallization of hydrogen under compression, are lacking for most high-pressure phases, owing to the considerable technical challenges involved in X-ray and neutron diffraction measurements under extreme conditions. Here we present a single-crystal X-ray diffraction study of solid hydrogen at pressures of up to 254 gigapascals that reveals the crystallographic nature of the transitions from phase I to phases III and IV. Under compression, hydrogen molecules remain in the hexagonal close-packed (hcp) crystal lattice structure, accompanied by a monotonic increase in anisotropy. In addition, the pressure-dependent decrease of the unit cell volume exhibits a slope change when entering phase IV, suggesting a second-order isostructural phase transition. Our results indicate that the precursor to the exotic two-component atomic hydrogen may consist of electronic transitions caused by a highly distorted hcp Brillouin zone and molecular-symmetry breaking.

National Category
Condensed Matter Physics Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-395792 (URN)10.1038/s41586-019-1565-9 (DOI)000488247600053 ()31554980 (PubMedID)
Funder
Swedish Research CouncilCarl Tryggers foundation
Available from: 2019-10-25 Created: 2019-10-25 Last updated: 2019-10-25Bibliographically approved
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