Superconducting <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>LaP</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">H</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> with graphenelike phosphorus layers
Xing Li, Xiaohua Zhang, Aitor Bergara, Guoying Gao, Yong Liu, Guochun Yang
Abstract
Novel structural building blocks in compounds could induce interesting physical and chemical properties. Although phosphorus tends to form very different motifs, the existence of lone pair electrons has always prevented the formation of graphenelike structures. Here, the application of first-principles swarm structural calculations has allowed us to predict the stability of pressure-induced hexagonal ${\mathrm{LaP}}_{2}{\mathrm{H}}_{2}$ containing graphenelike phosphorus, which derives from the trigonal bipyramid configuration of P atoms regulated by symmetric hydrogen bonds. ${\mathrm{LaP}}_{2}$ in ${\mathrm{LaP}}_{2}{\mathrm{H}}_{2}$ has the same configuration as ${\mathrm{MgB}}_{2}$, and P and H atoms form a three-dimensional framework as ${\mathrm{H}}_{3}\mathrm{S}$. Interestingly, ${\mathrm{LaP}}_{2}{\mathrm{H}}_{2}$ shows a superconductivity dominated by the graphenelike phosphorus layer and its coupling with La atoms. On the other hand, ${\mathrm{LaP}}_{2}{\mathrm{H}}_{2}$ is not only superconducting at a lower pressure than the H-rich ${\mathrm{LaPH}}_{6}$, but it also shows a superconducting transition temperature three times higher. Our work provides an example which extends the landscape of conventional superconductors at lower pressures.