Matter and Radiation at Extremes, Volume. 5, Issue 2, 28201(2020)
Superconductivity in La and Y hydrides: Remaining questions to experiment and theory
Fig. 1. Clathrate structures of typical metal superhydrides (polyhydrides).
Fig. 2. Predicted superconductivity in LaH10 and YH10 superhydrides.
Fig. 3. X-ray diffraction of LaH10 sample after laser heating at 175 GPa and 169 GPa.
Fig. 4. Resistivity studies of superconductivity in LaH10.
Fig. 5. Observed volumes per formula unit before and after the conversion from La to LaH10±x for several samples probed by resistivity technique.
Fig. 6. Transition to a lower symmetry phase (R-3m) in LaH10 on decompression from ∼170 GPa.
Fig. 7. Left panel: Schematic representation of the background subtraction principle in magnetic susceptibility measurements: 1. primary coil; 2. secondary compensating coil; 3. secondary signal coil. Further experimental details can be found in Ref.
Fig. 8. Left panel shows the magnetic response signals from the LaH10 sample in a DAC. The superimposed signals at several pressures are shown by dots: blue—164 GPa, green—169 GPa, red—180 GPa; the background is shown as a red dashed line (approximated by 3rd degree polynomial). Right panel: Signal after background subtraction, shifted in vertical direction (from bottom to top: blue—164 GPa, green—169 GPa, red—180 GPa).
Fig. 9. Calibration curves for two setups operating at two different excitation frequencies.
Fig. 10. Summary of the available experimental and theoretical data of superconductivity in LaH10. Sources for the data: Somayazulu
Fig. 11. Troyan
Fig. 12. Troyan
Fig. 13. Semenok
Fig. 14. High-Tc superconducting superhydrides,
Fig. 15. Comparison of atomic volumes per hydrogen atom in high-Tc and nonsuperconducting hydrides. The equation of state for hypothetical atomic hydrogen (green dashed line) is taken from Pepin
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Viktor Struzhkin, Bing Li, Cheng Ji, Xiao-Jia Chen, Vitali Prakapenka, Eran Greenberg, Ivan Troyan, Alexander Gavriliuk, Ho-kwang Mao. Superconductivity in La and Y hydrides: Remaining questions to experiment and theory[J]. Matter and Radiation at Extremes, 2020, 5(2): 28201
Category: High Pressure Physics and Materials Science
Received: Sep. 29, 2019
Accepted: Jan. 20, 2020
Published Online: Apr. 1, 2020
The Author Email: Struzhkin Viktor (viktor.struzhkin@hpstar.ac.cn)