Dynamics and superconductivity in compressed lanthanum superhydride

Abstract

Recent computational studies have predicted that rare-earth superhydrides are promising high-temperature superconductors. Of these phases having very high hydrogen content (XH n , n >6, where X is the rare-earth atom) a cubic phase of lanthanum hydride, been recently synthesized at 170 GPa and identified as LaH 10±x in good agreement with theoretical predictions. The experiments found that the stability of the phase extended to lower pressure and a distorted form was found on decompression. Here we examine the nuclear quantum and anharmonic dynamics on LaH 10 , including the behavior of the hydrogen sublattice in comparison with the predicted atomic metallic hydrogen at higher pressure. We also examine the vibrational dynamics and electronic properties of the lower pressure phase of LaH 10 and find that superconducting T c decreases relative to cubic but remains relatively high (i.e., 229-245 K).

Evidence for Superconductivity above 260 K in Lanthanum Superhydride at Megabar Pressures

“…Both are predicted to have superconducting temperatures near room temperature, i.e., near 270 K at 210 GPa for LaH10 and 300 K at 250 GPa in YH10. The superhydride phases consist of an atomic hydrogen sublattice with H-H distances of ~1.1 Å, which are close to the predicted values for solid atomic metallic hydrogen at these pressures [12]; for a thorough recent review of the field, see Ref. [13].…”

“…Experimental and theoretical constraints on the hydrogen content give a stoichiometry of LaH10±x, where ±x is between +2 and -1 [14]. On decompression, the fcc-based structure undergoes a rhombohedral distortion of the La sublattice, to form a structure that has subsequently been predicted to also have a high Tc [12].…”

A Critical Review of Machine Learning of Energy Materials

“…The error for predicting T cr has been shown to be within 1 K in some elemental systems, ranging from weak‐coupling (Mo,Al,Ta) to strong‐coupling (Nb,Pb) superconductors . This has led to the successful prediction and confirmation of new superconductors, including high pressure Si and Li, FeB 4 , H 2 S (or H 3 S), SnBi 2 Se 4 and PbBi 2 Te 4 , and recently NaH 10 . These successes, coupled with the development of databases of superconductors, have made ML an interesting new tool in the search of novel superconductors, particularly since the mechanisms for superconducting behavior differ from system to system .…”

Layered Cuprates Containing Flat Fragments: High-Pressure Synthesis, Crystal Structures and Superconducting Properties

“…These new exciting materials belong to conventional superconductors with properties that can be described by the Bardeen–Cooper–Schrieffer and the Migdal–Eliashberg theories. In addition, first-principles calculations based on density functional theory and recently developed non-adiabatic theory are used for explanation and prediction of properties of new superconducting materials [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. The latest results increase significantly interest in high pressure research and one can hope for further rapid progress in this direction.…”