High-temperature superconductivity in cubic lanthanum hydride La₄H₂₃ below 100 GPa

The discovery of superconductivity at 200 K in sulfur hydride, H₃S, at megabar pressures reignited the search for high-temperature superconductivity amongst compressed hydride compounds [1]. Since then, numerous superconducting hydride phases have been characterised, with the current record T_c of 250 K at 180 GPa (1.8 Mbar) in lanthanum hydride LaH₁₀, independently confirmed in multiple studies [2, 3]. However, the coexistence of a multitude of phases and stoichiometries at a given pressure presents a severe experimental challenge to synthesise single-phase hydrides, yet is critical for detailed study of the intrinsic superconducting properties. In this talk I present the synthesis and characterisation of a high-Tc lanthanum hydride thin-film at 95 GPa. X-ray diffraction confirms the presence of the cubic La₄H₂₃ structure with space group Pm-3n, a novel phase discovered in a recent single-crystal x-ray diffraction study [4]. In this sample, we observe a single superconducting transition with T_c ∼ 90 K in resistance measurements in agreement with recent work [5], and the suppression of T_c in magnetic field up to 12 T. This work highlights one of the first reports of superconductivity in La₄H₂₃ and further demonstrates the importance of exploring hydride phases at moderate pressures.

Phys. Rev. B 109, L020503



References

[1] A. Drozdov et al. Nature, vol. 525, p. 73, 2015.

[2] A. Drozdov et al. Nature, vol. 569, p. 528, 2019.

[3] M. Somayazulu et al. Physical review letters, vol. 122, p. 027001, 2019.

[4] D. Laniel et al. Nature Communications, vol. 13, p. 6987, 2022.

[5] J. Guo et al. National Science Review, 2024.