Modulating charge density wave states in TaSe2 by an electride substrate

Abstract

Modulating charge density wave (CDW) states in layered materials has both fundamental scientific value and application potential in future electronic devices. Based on first-principles electronic structure calculations, we have studied the modulation of the CDW states in ${\mathrm{TaSe}}_{2}$ by using a typical electride ${\mathrm{Ca}}_{2}\mathrm{N}$ as the substrate. We find that the ${\mathrm{Ca}}_{2}\mathrm{N}$ monolayer can donate 0.49 electrons/f.u. to the ${\mathrm{TaSe}}_{2}$ monolayer and meanwhile avoids the disorder effect in conventional chemical substitution approach. With the uniform electron doping from ${\mathrm{Ca}}_{2}\mathrm{N}$, the CDW order in $1H\ensuremath{-}{\mathrm{TaSe}}_{2}$ is completely suppressed; in comparison, the CDW period in $1T\ensuremath{-}{\mathrm{TaSe}}_{2}$ transforms from the Star of David pattern to a $\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3}$ triangular pattern. Our studies enrich the phase diagram of ${\mathrm{TaSe}}_{2}$ and highlight the effective manipulation of the CDW states via an electride substrate, which calls for future experimental verification.