<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>La</mml:mi><mml:msub><mml:mi>BH</mml:mi><mml:mn>8</mml:mn></mml:msub></mml:mrow></mml:math>: Towards high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>T</mml:mi><mml:mi>c</mml:mi></mml:msub></mml:math> low-pressure superconductivity in ternary superhydrides
Simone Di Cataldo, Christoph Heil, Wolfgang von der Linden, Lilia Boeri
Abstract
In the last five years a large number of new high-temperature superconductors have been predicted and experimentally discovered among hydrogen-rich crystals, at pressures, which are way too high to meet any practical application. In this paper, we report the computational prediction of a hydride superconductor, $\mathrm{La}{\mathrm{BH}}_{8}$, with a ${T}_{\text{c}}$ of 126 K at a pressure of 50 GPa, thermodynamically stable above 100 GPa, and dynamically stable down to 40 GPa, an unprecedentedly low pressure for high-${T}_{\text{c}}$ hydrides. $\mathrm{La}{\mathrm{BH}}_{8}$ can be seen as a ternary sodalite-like hydride, in which a metallic hydrogen sublattice is stabilized by the chemical pressure exerted by the La-B scaffolding, which achieves a more efficient packing of atoms than in binary sodalite hydrides thanks to the combination of elements with very different sizes. The proposed aufbau principle may be exploited to design high-${T}_{\text{c}}$ hydrides that survive at even lower pressure, through a careful choice of the elements.