Effect of uniaxial pressure on charge transport in the layered manganiteLa1.25Sr1.75Mn2O7

Abstract

The effect of uniaxial pressure on resistivity along the ab plane $({\ensuremath{\rho}}_{ab})$ and $c$ axis $({\ensuremath{\rho}}_{c})$ in single crystals of bilayer manganite ${\mathrm{La}}_{1.25}{\mathrm{Sr}}_{1.75}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ has been investigated. A prominent finding is the asymmetric role of pressure on charge transport phenomenon. With increasing pressure along the $c$ axis, ${\ensuremath{\rho}}_{ab}$ decreases and the metal-insulator (MI) transition temperature shifts towards higher temperature at the rate of $46\phantom{\rule{0.3em}{0ex}}\mathrm{K}∕\mathrm{GPa}$. In contrary to this, ${\ensuremath{\rho}}_{c}$ increases and the MI transition temperature decreases with increasing pressure along the ab plane. The resistivity ratio ${\ensuremath{\rho}}_{c}∕{\ensuremath{\rho}}_{ab}$ is quite large, increases with pressure, and shows a peak at around the MI transition. We believe that the unusual behavior of transport properties is related to the $\mathrm{Mn}\text{\ensuremath{-}}\mathrm{O}\text{\ensuremath{-}}\mathrm{Mn}$ linkage between ${\mathrm{MnO}}_{2}$ layers and the spin reorientation from the $c$ axis to the basal plane and vice versa with pressure.