Inverse order-disorder transition of charge stripes

Abstract

We report an unusual transition behavior of charge stripes in ${\mathrm{La}}_{1.67}{\mathrm{Sr}}_{0.33}{\mathrm{NiO}}_{4}$ using x-ray scattering. The segregated holes in ${\mathrm{La}}_{1.67}{\mathrm{Sr}}_{0.33}{\mathrm{NiO}}_{4}$ are observed to form anisotropic stripes in the $a\ifmmode\times\else\texttimes\fi{}b$ plane of the crystal space below the transition temperature $T\ensuremath{\simeq}238$ K, and at the same time, display an unusual inverse order-disorder transition along the $c$ axis. Using a phenomenological Landau theory, we show that this inverse transition is due to the interlayer coupling between the charge and spin orders. This discovery points to the importance of the interlayer correlations in the strongly correlated electrons system.