Two-dimensional superconductivity in stripe-orderedLa1.6−xNd0.4SrxCuO4single crystals

Abstract

The dc and ac magnetizations of the stripe-ordered ${\text{La}}_{1.6\ensuremath{-}x}{\text{Nd}}_{0.4}{\text{Sr}}_{x}{\text{CuO}}_{4}$ $(x=0.10,0.15,0.18)$ single crystals have been studied systematically under different magnetic-field orientations. It is found that the dc magnetizations $M$ for all the three different doped samples show two diamagnetic steps for $H\ensuremath{\parallel}c$, while there is only one for $H\ensuremath{\parallel}ab$. The real part ${M}^{\ensuremath{'}}$ of the ac magnetization is similar to that of the dc one and the imaginary part ${M}^{\ensuremath{''}}$ shows two peaks at the temperatures corresponding to the two steps of ${M}^{\ensuremath{'}}$. For comparison, the dc magnetization of ${\text{La}}_{1.85}{\text{Sr}}_{0.15}{\text{CuO}}_{4}$ single crystal without static stripe phase has only one transition for $H\ensuremath{\parallel}c$. The results suggest that the anisotropic magnetic properties in ${\text{La}}_{1.6\ensuremath{-}x}{\text{Nd}}_{0.4}{\text{Sr}}_{x}{\text{CuO}}_{4}$ are closely related to the decoupling between the ${\text{CuO}}_{2}$ planes by the static stripe order which causes a two-dimensional superconducting state in the system.