Revealing the competition between charge density wave and superconductivity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:msub><mml:mi>CsV</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mi>Sb</mml:mi></mml:mrow><mml:mn>5</mml:mn></mml:msub></mml:math> through uniaxial strain

In this paper we report the impact of uniaxial strain $\varepsilon$ applied along crystalline $a$ axis on newly discovered kagome superconductor CsV$_3$Sb$_5$. At ambient conditions, CsV$_3$Sb$_5$ shows a charge-density wave (CDW) transition at $T_{\rm CDW}=94.5$ K and superconducts below $T_C = 3.34$ K. our study, when is varied from $-0.90\%$ to $0.90\%$, $T_C$ monotonically increases by $\sim 33\%$ 3.0 4.0 K, giving rise empirical relation (\varepsilon)=3.4+0.56\varepsilon+0.12\varepsilon^2$. On other hand, for changing $-0.76\%$ $1.26\%$, CDW}$ decreases 10\%$ 97.5 87.5 with CDW}(\varepsilon)=94.5-4.72\varepsilon-0.60\varepsilon^2$. The opposite response suggests strong competition between these two orders. Comparison hydrostatic pressure measurements indicate that it change in $c$-axis responsible behaviors CDW superconducting transitions, explicit breaking sixfold rotational symmetry has negligible effect. Combined first-principles calculations phenomenological analysis, conclude enhancement decreasing $c$ caused primarily suppression CDW}$, rather than strain-induced modifications bare parameters. We propose sensitivity respect changes arises latter trilinear coupling $M_1^+$ $L_2^-$ phonon modes associated CDW. Overall, work reveals lattice parameter, which can be controlled both strain, powerful tuning knob phase diagram