Correlation between Structural and Magnetic Properties in Sr$_{3}$(Ru$_{1-x}$Mn$_{x})_{2}$O$_{7}$ Single Crystals

We have studied the Mn-doping (x) dependence of structural and magnetic properties in Sr$_{3}$(Ru$_{1-x}$Mn$_{x})_{2}$O$_{7 }$. The system remains tetragonal as determined by single-crystal X-ray diffraction with the lattice parameters $a$ and $c$ varying with x. Correspondingly, the value of Jahn-Teller distortion ($\Delta _{JT})$ of (Ru,Mn)O$_{6}$ octahedron decreases with increasing x with $\Delta _{JT }$= 1.0 for x$\sim $0.5. At the same doping level, we note the sign change of Curie-Weiss temperature $\Theta _{CW}$ derived from high-temperature magnetic susceptibility. The correlation between structural and magnetic properties will be discussed.