Oxygen isotope effect on the superconductivity and stripe phase inLa1.6−xNd0.4SrxCuO4

Abstract

The oxygen isotope effect on the superconductivity, stripe phase, and structure transition is systematically investigated in ${\mathrm{La}}_{1.6\ensuremath{-}x}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{x}\mathrm{Cu}{\mathrm{O}}_{4}$ with static stripe phase. Substitution of $^{16}\mathrm{O}$ by $^{18}\mathrm{O}$ leads to a decrease in superconducting transition temperature ${T}_{C}$ while enhancing the temperature of the structural transition from low-temperature-orthorhombic phase to low-temperature-tetragonal phase. Compared to the Nd-free sample, a larger isotope effect on ${T}_{C}$ is observed in ${\mathrm{La}}_{1.6\ensuremath{-}x}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{x}\mathrm{Cu}{\mathrm{O}}_{4}$. These results indicate that the distortion of $\mathrm{Cu}{\mathrm{O}}_{2}$ plane suppresses the superconductivity, giving a direct evidence of the competition of stripe phase and superconductivity because the distortion of $\mathrm{Cu}{\mathrm{O}}_{2}$ plane enhances the stripe phase.