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Superconductivity at 250 K in lanthanum hydride under high pressures

Abstract

With the discovery1 of superconductivity at 203 kelvin in H3S, attention returned to conventional superconductors with properties that can be described by the Bardeen–Cooper–Schrieffer and the Migdal–Eliashberg theories. Although these theories predict the possibility of room-temperature superconductivity in metals that have certain favourable properties—such as lattice vibrations at high frequencies—they are not sufficient to guide the design or predict the properties of new superconducting materials. First-principles calculations based on density functional theory have enabled such predictions, and have suggested a new family of superconducting hydrides that possess a clathrate-like structure in which the host atom (calcium, yttrium, lanthanum) is at the centre of a cage formed by hydrogen atoms2,3,4. For LaH10 and YH10, the onset of superconductivity is predicted to occur at critical temperatures between 240 and 320 kelvin at megabar pressures3,4,5,6. Here we report superconductivity with a critical temperature of around 250 kelvin within the \(Fm\bar{{\bf{3}}}m\) structure of LaH10 at a pressure of about 170 gigapascals. This is, to our knowledge, the highest critical temperature that has been confirmed so far in a superconducting material. Superconductivity was evidenced by the observation of zero resistance, an isotope effect, and a decrease in critical temperature under an external magnetic field, which suggested an upper critical magnetic field of about 136 tesla at zero temperature. The increase of around 50 kelvin compared with the previous highest critical temperature1 is an encouraging step towards the goal of achieving room-temperature superconductivity in the near future.

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Acknowledgements

M.I.E. thanks the Max Planck Society and the MPI for Chemistry for support, U. Pöschl for encouragement, R. Wittkowski and the staff of the mechanical workshop of the MPI for Chemistry for technical support. We thank S. Sutton for discussion. L.B. is supported by DOE-BES through award DE-SC0002613. S.M. acknowledges support from the FSU Provost Postdoctoral Fellowship Program. The National High Magnetic Field Laboratory acknowledges support from the US NSF Cooperative Grant number DMR-1644779 and the state of Florida. Portions of this work were performed at GeoSoilEnviro CARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviro CARS is supported by the National Science Foundation – Earth Sciences (EAR – 1634415) and Department of Energy – GeoSciences (DE-FG02-94ER14466). This research used resources of the Advanced Photon Source, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract number DE-AC02-06CH11357.

Reviewer information

Nature thanks James J. Hamlin and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Author information

A.P.D., P.P.K., V.S.M., S.P.B., M.A.K., M.T. and D.A.K. prepared the samples and measured the superconducting transition. S.M., F.F.B., L.B. and D.E.G. performed studies under external magnetic fields. V.B.P., E.G., V.S.M. and M.A.K. performed X-ray diffraction studies. M.I.E., V.S.M. and S.M. wrote the manuscript, with input from all co-authors. M.I.E. guided the work.

Competing interests

The authors declare no competing interests.

Correspondence to M. I. Eremets.

Extended data figures and tables

  1. Extended Data Fig. 1 Characterization of samples synthesized from a mixture of La + H2 (in deficiency) at 150–180 GPa that exhibit superconductivity at around 70 K and around 110 K.

    a, b, Photographs of sample 9 exhibiting superconductivity with Tc ≈ 108 K after laser heating. Photos are taken in the combined transmitting–reflecting illumination before (a) and after (b) laser heating at around 1,000 K at 152 GPa. After thermal treatment, the size of the sample increased considerably and it started to reflect the incident light. c, Typical integrated X-ray powder patterns for different samples synthesized from lanthanum heated in H2 (in deficiency). We were unable to index the patterns from a complicated mixture of different phases. The black plot corresponds to sample 9 synthesized at 152 GPa with Tc ≈ 108 K. The blue and olive plots correspond to samples 10 and 11 synthesized at 178 GPa (Tc ≈ 112 K) and 150 GPa (Tc ≈ 70 K), respectively. The red plot and red stars indicate the \(Fm\bar{3}m\) phase of LaH3 (two of the samples also contain some LaH3 phase). d, The integrated X-ray powder pattern of sample 10 shown in b measured in the centre of the sample. It indicates an almost pure \(Fm\bar{3}m\) phase of LaH3. Black, red and blue plots correspond to experimental data, fitted data, and the difference between experimental and fitted data, respectively. e, The distribution of the fcc phase of LaH3 in the heated sample 10, shown in b, obtained from mapping the sample with an X-ray focused beam. The brightest part in the centre corresponds to the powder pattern presented in d.

  2. Extended Data Fig. 2 Superconductive transitions occurring in different samples prepared from a mixture of La + H2, when H2 is taken in deficiency.

    Resistance was normalized to the value at 300 K for each sample. The unheated sample 10 at 178 GPa (black plot) shows the onset of the superconducting transition at around 70 K, which shifts with a magnetic field of 5 T to about 49 K (red plot). The same superconducting phase (Tc ≈ 70 K; magenta plot) was found in another sample (sample 11) prepared at 150 GPa by laser heating of the La + H2 mixture (in a large deficiency of H2). After subsequent gradual laser heating of the first sample (black plot) up to about 1,500 K, the sample absorbed the rest of the hydrogen, its volume increased, and a new superconductive transition appeared at around 112 K (blue plot). After several heating cycles, only one sharp transition at 112 K remained (green plot). The Tc was determined from the onset of superconductivity, at the intersection of the temperature dependence of resistance in the normal and superconducting states (blue lines in the blue plot).

  3. Extended Data Fig. 3 Superconductivity in sample 12 synthesized at around 160 GPa from a mixture of lanthanum and an excess of H2.

    a, b, View of the sample inside the diamond anvil cell with the attached four electrodes at transmission illumination before (a) and after (b) laser heating. As a result of heating, the sample increased considerably in volume and nearly filled the whole sample space, but was still surrounded by hydrogen. c, Superconducting steps shown by the temperature dependence of the resistance at different pressures. The pressure dependence of the onset of superconductivity is shown in the inset: Tc shifts to higher temperatures as the pressure is decreased.

  4. Extended Data Fig. 4 Lanthanum samples heated by a laser in an excess of deuterium.

    a, Photograph of the heated LaD11 sample (13) at 139 GPa, taken in transmission illumination mode. b, Superconducting transitions at different pressures (the pressure was determined from the D2 vibron scale29). The inset shows the pressure dependence of Tc measured for different samples (red, black, green and blue points correspond to samples 8, 13, 15 and 16, respectively). The refined crystal structure for red, blue and green points corresponds to the tetragonal P4/nmm lattice and LaD11 stoichiometry.

  5. Extended Data Fig. 5 Superconducting transitions in hydrides synthesized from lanthanum in hydrogen and deuterium atmospheres.

    Lanthanum hydrides: Tc ≈ 250 K (sample 1), Tc ≈ 215 K (sample 12), Tc ≈ 110 K (sample 10), Tc ≈ 70 K (sample 11); lanthanum deuterides: Tc ≈180 K (sample 17), Tc ≈ 165 K (sample 13), Tc ≈ 140 K (sample 8) and Tc ≈ 80 K (sample 14). The thick curves show the R(T) dependences of the samples with fcc-LaH10 and fcc-LaD10 phases.

  6. Extended Data Fig. 6 Superconductivity in lanthanum deuteride with the fcc-LaD10 phase.

    a, The X-ray diffraction pattern of sample 17 before laser heating contains fcc-LaD10 as well as hcp-I and hcp-II LaH10 phases, and an unidentified transparent phase. The sample was synthesized at around 120 GPa by heating a piece of lanthanum in a deuterium atmosphere. The temperature dependence of resistance measured at 152 GPa reveals a superconducting transition with Tc ≈ 180 K. b, As a result of successive laser heating to 2,150 K, a considerable amount of the fcc-LaD10 phase transformed into the P4/nmm LaD11 phase, while diffraction patterns from the impurities hcp-I, hcp-II and the unidentified transparent phases remained almost unchanged. c, In accordance with the structural change, a new peak on the R(T) graph appeared at around 140 K. In fact, the shape of the R(T) plot indicates a superconducting transition, as is observed in granular disordered systems (see, for instance, ref. 25). In this case, the onset of superconductivity should be taken at a temperature when the peak starts to develop—that is, at 155–160 K, as indicated by the arrow. The subtle step at around 187 K on the red curve after laser heating relates to the remains of the fcc-LaD10 phase.

  7. Extended Data Fig. 7 X-ray powder diffraction analysis for sample 18 exhibiting a high Tc of approximately 180 K.

    a, Typical integrated X-ray powder diffraction pattern for sample 18 (black curve). The experimental powder pattern is obviously complex; nevertheless, most reflections can be indexed as corresponding to two phases: fcc-LaD10 (red pattern) and hcp-II LaD10 (blue pattern). b, The reflections from the fcc-LaD10 phase are represented as separate spots, indicated by the red circles in the cake representation of the X-ray powder diffraction pattern.

Supplementary information

  1. Supplementary Table

    This file contains Supplementary Table 1, a list of Samples.

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Fig. 1: The observation of superconductivity in LaH10.
Fig. 2: Superconducting transition under an external magnetic field.
Fig. 3: Structural analysis.
Fig. 4: The isotope effect.
Extended Data Fig. 1: Characterization of samples synthesized from a mixture of La + H2 (in deficiency) at 150–180 GPa that exhibit superconductivity at around 70 K and around 110 K.
Extended Data Fig. 2: Superconductive transitions occurring in different samples prepared from a mixture of La + H2, when H2 is taken in deficiency.
Extended Data Fig. 3: Superconductivity in sample 12 synthesized at around 160 GPa from a mixture of lanthanum and an excess of H2.
Extended Data Fig. 4: Lanthanum samples heated by a laser in an excess of deuterium.
Extended Data Fig. 5: Superconducting transitions in hydrides synthesized from lanthanum in hydrogen and deuterium atmospheres.
Extended Data Fig. 6: Superconductivity in lanthanum deuteride with the fcc-LaD10 phase.
Extended Data Fig. 7: X-ray powder diffraction analysis for sample 18 exhibiting a high Tc of approximately 180 K.

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