A Metastable CaSH$_3$ Phase Composed of HS Honeycomb Sheets that is Superconducting Under Pressure
| Autor: | Xiaoyu Wang, Nisha Geng, Tiange Bi, Eva Zurek, Yan Yan |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Superconductivity
Materials science Condensed Matter - Superconductivity Fermi level FOS: Physical sciences 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Metal Bond length Superconductivity (cond-mat.supr-con) Crystallography symbols.namesake Metastability visual_art 0103 physical sciences Density of states visual_art.visual_art_medium symbols Molecule General Materials Science Physical and Theoretical Chemistry 010306 general physics 0210 nano-technology Ternary operation |
| DOI: | 10.48550/arxiv.2012.14985 |
| Popis: | Evolutionary searches predicted a number of ternary phases that could be synthesized at pressures of 100-300~GPa. $P6_3/mmc$ CaSH$_2$, $Pnma$ CaSH$_2$, $Cmc2_1$ CaSH$_6$, and $I\bar{4}$ CaSH$_{20}$ were composed of a Ca-S lattice along with H$_2$ molecules coordinated in a ``side-on'' fashion to Ca. The H-H bond lengths in these semiconducting phases were elongated because of H$_2$ $\sigma\rightarrow$ Ca d donation, and Ca d$\rightarrow$ H$_2$ $\sigma^*$ back-donation, via a Kubas-like mechanism. $P\bar{6}m2$ CaSH$_3$, consisting of two-dimensional HS and CaH$_2$ sheets, was metastable and metallic above \edit{128~GPa}. The presence of van Hove singularities increased its density of states at the Fermi level, and concomitantly the superconducting critical temperature, which was estimated to be as high as \edit{$\sim$100~K at 128~GPa}. This work will inspire the search for superconductivity in materials based upon \edit{honeycomb HX (X=S, Se, Te), and MH$_2$ (M=Mg, Ca, Sr, Ba) layers} under pressure. |
| Databáze: | OpenAIRE |
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