Dependence of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>T</mml:mi><mml:mtext>c</mml:mtext></mml:msub></mml:math> of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>YBa</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Cu</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>6.67</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> on in-plane uniaxial stress

We probe the effect on ${T}_{\text{c}}$ of in-plane uniaxial stress applied to the high-temperature superconductor ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6.67}$. We find a highly anisotropic response. Under compression along the $b$ axis, which reduces the orthorhombicity of the ${\mathrm{CuO}}_{2}$ planes, ${T}_{\text{c}}$ is broadly flat for stresses up to at least 1.7 GPa. Under compression along the $a$ axis, ${T}_{\text{c}}$ decreases steeply. For stresses beyond $\ensuremath{\approx}1$ GPa the decrease is quasilinear. We hypothesize that superconductivity is suppressed by competition with uniaxial charge density wave order, which has been found to onset at $\ensuremath{\approx}1$ GPa.