Superconductivity above 105 K in Nonclathrate Ternary Lanthanum Borohydride below Megabar Pressure
Xiaoxu Song, Xiaokuan Hao, Xudong Wei, Xin‐Ling He, Hanyu Liu, Liang Ma, Guangtao Liu, Hongbo Wang, Jingyu Niu, Shaojie Wang, Yanpeng Qi, Zhongyuan Liu, Wentao Hu, Bo Xu, Lin Wang, Guoying Gao, Yongjun Tian
Abstract
Hydrides are promising candidates for achieving room-temperature superconductivity, but a formidable challenge remains in reducing the stabilization pressure below a megabar. In this study, we successfully synthesized a ternary lanthanum borohydride by introducing the nonmetallic element B into the La–H system, forming robust B–H covalent bonds that lower the pressure required to stabilize the superconducting phase. Electrical transport measurements confirm the presence of superconductivity with a critical temperature ( T c ) of up to 106 K at 90 GPa, as evidenced by zero resistance and T c shift under an external magnetic field. X-ray diffraction and transport measurements identify the superconducting compound as LaB 2 H 8, a nonclathrate hydride, whose crystal structure remains stable at pressures as low as ∼ half megabar (59 GPa). Stabilizing superconductive stoichiometric LaB 2 H 8 in a submegabar pressure regime marks a substantial advancement in the quest for high- T c superconductivity in polynary hydrides, bringing us closer to the ambient pressure conditions.