Commensurate-incommensurate magnetic phase transition in the Fe-doped ruthenate bilayer Ca$_{3}$Ru$_{2}$O$_{7}$

Neutron diffraction studies have revealed an uncommon commensurate-incommensurate magnetic phase transition with decreasing temperature in the ($\sim$ 5{\%}) Fe-doped bilayer ruthenate Ca$_{3}$(Ru,Fe)$_{2}$O$_{7}$. An incommensurate phase formed of a cycloidal spiral spin structure coexists with a commensurate one below the phase transition at 42 K and persists down to the lowest temperature, accompanied by higher-order magnetic satellite peaks which indicate the formation of a magnetic soliton lattice. We ascribe these findings to the competing magnetic interactions in Ca$_{3}$Ru$_{2}$O$_{7}$. This study demonstrates an effective approach to tune novel magnetic and electronic properties of this complex system via 3d magnetic transition-metal substitution. \\[4pt] [1] X. Ke et al, Phys. Rev. B. \textbf{89}. 220407 (R) (2014).