Tunable one-dimensional charge density waves induced by atomic-scale strain

Charge density waves (CDWs)---collective quantum states arising from coupled electron-lattice interactions---serve as critical probes of competing orders in quantum materials, including superconductivity and magnetism. Monolayer $1T\text{\ensuremath{-}}\mathrm{VS}{\mathrm{e}}_{2}$ presents a unique platform where CDWs display substrate-sensitive configurations distinct from bulk systems, challenging conventional formation paradigms. Through scanning tunneling microscopy, we reveal how uniaxial strain controls CDW dimensionality and periodicity in monolayer $1T\text{\ensuremath{-}}\mathrm{VS}{\mathrm{e}}_{2}$, generating two strain-direction-dependent stripelike phases: an incommensurate one-dimensional (1D) CDW ($|{Q}_{1}|=1/\sqrt{7}|{a}^{*}|$) at 30 \ifmmode^\circ\else\textdegree\fi{} strain orientation and a commensurate 1D CDW $({Q}_{2}=0.25{a}^{*})$ aligned with lattice vectors. These directional modulations stem from strain-enhanced momentum-selective electron-phonon coupling, which overrides traditional Fermi surface nesting mechanisms. Furthermore, we reveal that coexisting complex CDW features, previously observed, are fundamentally emergent moir\'e patterns resulting from the superposition of engineered 1D CDWs and the underlying atomic lattice. Our work resolves longstanding controversies in monolayer $1T\text{\ensuremath{-}}\mathrm{VS}{\mathrm{e}}_{2}$ and provides a universal framework for manipulating correlated phases in van der Waals materials through anisotropic lattice engineering.