The in-plane magnetic field penetration depth (${\lambda }_{\mathrm{ab}}$) in single-crystal ${\mathrm{La}}_{1.83}{\mathrm{Sr}}_{0.17}{\mathrm{CuO}}_4$ was investigated by muon-spin rotation ($\mu \mathrm{SR}$). The temperature dependence of ${\lambda }_{\mathrm{ab}}^{-2}$ has an inflection point around 10–15 K, suggesting the presence of two superconducting gaps: a large gap (${\Delta }_1^d$) with $d$-wave and a small gap (${\Delta }_2^s$) with $s$-wave symmetry. The zero-temperature values of the gaps at ${\mu }_{0}H=0.02\mathrm{T}$ were found to be ${\Delta }_1^d(0)=8.2(1)\mathrm{meV}$ and ${\Delta }_2^s(0)=1.57(8)\mathrm{meV}$.

• Received 7 June 2006

DOI:https://doi.org/10.1103/PhysRevLett.98.057007