High-temperature Conventional Superconductivity at High Pressures

Room-temperature superconductivity is one of the most challenging and long-standing problems in condensed-matter physics. I will discuss the significant progress reached in the field and focus on three main subjects: metallic hydrogen, super hydrides, and the perspectives to find high-Tc superconductors at moderate pressures.

In 2014, superconductivity at 203 K was discovered in H3S at high pressure, breaking archaic paradigms on conventional superconductivity [1]. Last year, with the advancement of the field, Tc of 250 K we had been reached in a super hydride LaH10 [2-3]. The mechanism governing these exceptional superconductors is the conventional electron-phonon coupling [5]. Theoretically, predictions point out other compositions that could superconduct at temperatures as high as 470 K [6]. These record-breaking superconductors are the result of chasing of a 50 years old prediction of high-temperature superconductivity in hydrogen [7-8]. In this respect, we will present the most recent efforts on seeking for the superconducting phase of hydrogen [9]. The progress towards room temperature superconductivity is likely to be related to hydrides under pressure [5]. I will outline perspectives for high-temperature conventional superconductivity at moderate and ambient pressure which is expected from arrangements of atoms of light elements.

References
[1] Drozdov, A. P., Eremets, M. I., Troyan, I. A., Ksenofontov, V. & Shylin, S. I. Conventional superconductivity at 203 K at high pressures. Nature 525, 73 (2015).
[2] Drozdov, A. P. et al. Superconductivity at 250 K in lanthanum hydride under high pressures. Nature 569, 528 (2019).
[3] Somayazulu, M. et al, Evidence for Superconductivity above 260 K in Lanthanum Superhydride at Megabar Pressures. Phys. Rev. Lett. 122, 027001 (2019).
[4] I. Errea, F. Belli, L. Monacelli, A. Sanna, T. Koretsune, T. Tadano, R. Bianco, M. Calandra, R. Arita, F. Mauri and J. A. Flores-Livas. Quantum Crystal Structure in the 250 K Superconducting Lanthanum Hydride. Nature, (2020).
[5] J. A. Flores-Livas, L. Boeri, A. Sanna, R. Arita, M. Eremets. A Perspective on Conventional High-Temperature Superconductors at High Pressure: Methods and Materials. Review on Physics Reports (2020).
[6] Sun, Y., Lv, J., Xie, Y., Liu, H. & Ma, Y. The route to a Superconducting Phase above Room Temperature in Electron-Doped Hydride Compounds under High Pressure. Phys. Rev. Lett. 123, 097001 (2019).
[7] Ashcroft, N. W. Metallic hydrogen: A high-temperature superconductor? Phys. Rev. Lett. 21, 1748 (1968).
[8] Ashcroft, N. W. Hydrogen Dominant Metallic Alloys: High-Temperature Superconductors? Phys. Rev. Lett. 92, 187002 (2004).
[9] Eremets, M. I., Drozdov, A. P., Kong, P. P. & Wang, H. Semimetallic molecular hydrogen at a pressure above 350 GPa. Nature Physics, 15, 1246 (2019).