Effects of uniaxial stress on orbital stripe direction in half-doped layered manganites:Eu0.5Ca1.5MnO4andPr(Sr,Ca)2Mn2O7

Abstract

We have studied the uniaxial-stress effects on the half-doped charge-orbital ordered (CO-OO) manganites ${\text{Eu}}_{0.5}{\text{Ca}}_{1.5}{\text{MnO}}_{4}$ and $\text{Pr}{({\text{Sr}}_{1\ensuremath{-}y}{\text{Ca}}_{y})}_{2}{\text{Mn}}_{2}{\text{O}}_{7}(y\ensuremath{\sim}0.9)$. ${\text{Eu}}_{0.5}{\text{Ca}}_{1.5}{\text{MnO}}_{4}$ with single Mn-O layer structure is ferroelastic and the application of weak uniaxial stress $(<8.5\text{ }\text{MPa})$ along the orbital stripe direction drives a rotation of the orbital stripes by $90\ifmmode^\circ\else\textdegree\fi{}$ through the lattice orthorhombicity channel. For $\text{Pr}{({\text{Sr}}_{1\ensuremath{-}y}{\text{Ca}}_{y})}_{2}{\text{Mn}}_{2}{\text{O}}_{7}(y\ensuremath{\sim}0.9)$ with double Mn-O layer structure, it is revealed that the phase stability of two CO-OO states with different orbital stripe direction can be controlled by the external uniaxial pressure. In addition, the application of higher uniaxial pressure also causes a rotation of the lattice orthorhombicity itself and hence rotates the orbital stripes as well as the electric polarization axis in the low-temperature CO-OO state.