High pressure plays a crucial role in the field of superconductivity. Compressed hydride superconductors are leaders in the race for a material that can conduct electricity without resistance at high or even room temperature. In the present work, we have discovered new lanthanum superhydride, cubic A15-type La4H23, with lower stabilization pressure compared to the reported fcc LaH10. Superconducting La4H23 was obtained by laser heating of LaH3 with ammonia borane at about 120 GPa. Transport measurements reveal the maximum critical temperature TC(onset) = 105 K and the critical field HC2(0) = 32 T at 118 GPa, as evidenced by the sharp drop of electrical resistance and the displacement of superconducting transitions in applied magnetic fields. Moreover, we provide evidence for unconventional transport associated with a pseudogap phase in La4H23 using pulsed magnetic fields up to 68 T. A large negative magnetoresistance in the non-superconducting state below 40 K, quasi T-linear electrical resistance, and a sign-change of its temperature dependence mark the emergence of pseudogap in this hydride. Discovered lanthanum hydride is a new member of the A15 family of superconductors with TC exceeding the boiling point of liquid nitrogen.
@article{arxiv.2307.13067,
title = {Large negative magnetoresistance and pseudogap phase in superconducting A15-type La$_4$H$_{23}$},
author = {Jianning Guo and Dmitrii Semenok and Grigoriy Shutov and Di Zhou and Su Chen and Yulong Wang and Toni Helm and Sven Luther and Xiaoli Huang and Tian Cui},
journal= {arXiv preprint arXiv:2307.13067},
year = {2024}
}