According to theoretical predictions, insulating molecular hydrogen dissociates and transforms into an atomic metal at pressures P ≈ 370–500 GPa (refs. 1,2,3). In another scenario, the metallization first occurs in the 250–500 GPa pressure range in molecular hydrogen through overlapping of electronic bands4,5,6,7. The calculations are not accurate enough to predict which option is realized. Here, we show that at a pressure of 350–360 GPa and temperatures <200 K, the hydrogen starts to conduct, and that the temperature dependence of the electrical conductivity is typical of a semimetal. The conductivity, measured up to 440 GPa, increases strongly with pressure. Raman spectra, measured up to 480 GPa, indicate that hydrogen remains a molecular solid at pressures up to 440 GPa, while at higher pressures the Raman signal vanishes, probably indicating further transformation to a good molecular metal or to an atomic state.
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The data that support the findings of this study are available from the corresponding author upon reasonable request.
Wigner, E. & Huntington, H. B. On the possibility of a metallic modification of hydrogen. J. Chem. Phys. 3, 764–770 (1935).
Pickard, C. J. & Needs, R. J. Structure of phase III of solid hydrogen. Nat. Phys. 3, 473–476 (2007).
McMinis, J. III, Clay, R. C., Lee, D. & Morales, M. A. Molecular to atomic phase transition in hydrogen under high pressure. Phys. Rev. Lett. 114, 105305 (2015).
Johnson, K. A. & Ashcroft, N. W. Structure and bandgap closure in dense hydrogen. Nature 403, 632–635 (2000).
Rillo, G., Morales, M. A., Ceperley, D. M. & Pierleoni, C. Coupled electron–ion Monte Carlo simulation of hydrogen molecular crystals. J. Chem. Phys. 148, 102314 (2018).
Azadi, S., Singh, R. & Kuehne, T. D. Nuclear quantum effects induce metallization of dense solid molecular hydrogen. J. Comput. Chem. 39, 262–268 (2018).
Azadi, S., Drummond, N. D. & Foulkes, W. M. C. Nature of the metallization transition in solid hydrogen. Phys. Rev. B 95, 035142 (2017).
Azadi, S., Monserrat, B., Foulkes, W. M. C. & Needs, R. J. Dissociation of high-pressure solid molecular hydrogen: a quantum Monte Carlo and anharmonic vibrational study. Phys. Rev. Lett. 112, 165501 (2014).
Ashcroft, N. W. Metallic hydrogen: a high-temperature superconductor? Phys. Rev. Lett. 21, 1748–1750 (1968).
Dias, R. P. & Silvera, I. F. Observation of the Wigner-Huntington transition to metallic hydrogen. Science 355, 715–718 (2017).
Y.Geng, H. Public debate on metallic hydrogen to boost high pressure research. Matter Radiat. Extrem. 2, 275–277 (2017).
Eremets, M. I., Troyan, I. A. & Drozdov, A. P. Low temperature phase diagram of hydrogen at pressures up to 380 GPa. A possible metallic phase at 360 GPa and 200 K. Preprint at https://arXiv.org/abs/1601.04479 (2016).
Hazen, R. M., Mao, H. K., Finger, L. W. & Hemley, R. J. Single-crystal x-ray diffraction of n-H2 at high pressure. Phys. Rev. B 36, 3944–3947 (1987).
Akahama, Y. I. et al. Evidence from x-ray diffraction of orientational ordering in phase III of solid hydrogen at pressures up to 183 GPa. Phys. Rev. B 82, 060101(R) (2010).
Loubeyre, P. et al. X-ray diffraction and equation of state of hydrogen at megabar pressures. Nature 383, 702–704 (1996).
Loubeyre, P., Occelli, F. & LeToullec, R. Optical studies of solid hydrogen to 320 GPa and evidence for black hydrogen. Nature 416, 613–617 (2002).
Eremets, M. I., Troyan, I. A., Lerch, P. & Drozdov, A. Infrared study of hydrogen up to 310 GPa at room temperature. High. Press. Res. 33, 377–380 (2013).
Lebègue, S. et al. Semimetallic dense hydrogen above 260 GPa. Proc. Natl Acad. Sci. USA 109, 9766–9769 (2012).
Zha, C.-S., Liu, Z. & Hemley, R. J. Synchrotron infrared measurements of dense hydrogen to 360 GPa. Phys. Rev. Lett. 108, 146402 (2012).
Eremets, M. I., Drozdov, A. P., Kong, P. P. & Wang, H. Molecular semimetallic hydrogen. Preprint at https://arxiv.org/abs/1708.05217 (2017).
Eremets, M. I. & Troyan, I. A. Conductive dense hydrogen. Nat. Mater. 10, 927–931 (2011).
Brown, P., Semeniuk, K., Vasiljkovic, A. & MGrosche, F. Pressure-induced semimetal-to-semiconductor transition in bismuth. Phys. Procedia 75, 29–33 (2015).
Shimizu, K. Superconducting elements under high pressure. Phys. C 552, 30–33 (2018).
Eremets, M. I. et al. Electrical conductivity of Xe at megabar pressures. Phys. Rev. Lett. 85, 2797–2800 (2000).
Koufos, A. P. & Papaconstantopoulos, D. A. Pressure-induced insulator to metal transition and superconductivity of the inert gases. J. Supercond. Nov. Magn. 28, 3525–3533 (2015).
Ma, Y., Oganov, A. R. & Glass, C. W. Structure of the metallic ζ-phase of oxygen and isosymmetric nature of the ε−ζ-phase transition: ab initio simulations. Phys. Rev. B 76, 064101 (2007).
Goncharov, A. F., Gregoryanz, E., Hemley, R. J. & Mao, H. K. Molecular character of the metallic high-pressure phase of oxygen. Phys. Rev. B 68, 100102 (2003).
Shimizu, K., Eremets, M. I., Suhara, K. & Amaya, K. Oxygen under high pressure – temperature dependence of electrical resistance. Rev. High. Press. Sci. Technol. 7, 784–786 (1998).
Monserrat, B. et al. Structure and metallicity of phase V of hydrogen. Phys. Rev. Lett. 120, 255701 (2018).
Drummond, N. D. et al. Quantum Monte Carlo study of the phase diagram of solid molecular hydrogen at extreme pressures. Nat. Commun. 6, 7794 (2015).
Cerdeira, F., Dreybrodt, W. & Cardona, M. Resonant Raman scattering in germanium. Solid State Commun. 10, 591–595 (1972).
Monserrat, B., Needs, R. J., Gregoryanz, E. & Pickard, C. J. Hexagonal structure of phase III of solid hydrogen. Phys. Rev. B 94, 134101 (2016).
Eremets, M. I. Megabar high-pressure cells for Raman measurements. J. Raman Spectrosc. 34, 515–518 (2003).
Y. Akahama, Y. & Kawamura, H. Pressure calibration of diamond anvil Raman gauge to 410 GPa. J. Phys. C 215, 012195 (2010).
Support provided by the European Research Council under Advanced Grant 267777 is acknowledged. We acknowledge Th. Timusk, V. Kresin, L. Boeri, F. Balakirev, Sh. Mozaffari and D. Graf for helpful discussions and comments. M.I.E. is grateful to the Max Planck community for the invaluable support, and U. Pöschl for the constant encouragement.
The authors declare no competing interests.
Peer review information Nature Physics thanks Alexander Goncharov and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Eremets, M.I., Drozdov, A.P., Kong, P.P. et al. Semimetallic molecular hydrogen at pressure above 350 GPa. Nat. Phys. (2019) doi:10.1038/s41567-019-0646-x