Spin correlations in the ground state of NaSmMn2Ti4O12: A possible transition from high-temperature long-range ordered to low-temperature short-range correlated states

A new family of perovskite titanates NaRMn2Ti4O12 with R = Sm, Eu, Gd, Dy, Ho, Y has been recently obtained using high pressure synthesis. The members of the family crystallise into columnar quadruple-perovskite structure and show a long range magnetic order below 11-13K. Surprisingly, our previous neutron diffraction study revealed a second transition in Dy compound from high-temperature (T6K) ordered to low-temperature (T<6K) short-range correlated magnetic ground state. This is a very unusual transition, the nature of which is currently unclear. The aim of the present neutron diffraction experiment is to probe the long-range versus short range correlated ground state in the Sm perovskite which also shows two magnetic transitions on macroscopic measurements.