Observation of Spin Glassy Behavior in Sr₃(Ru_0.64Mn_0.36)₂O₇

One of the most accessible knobs to tune the ground state properties of a material system is chemical doping. Double-layered Ruddlesden-Popper ruthenate Sr₃Ru₂O₇ is known to respond dramatically to the substitution of Ru by Mn leading to a rich phase diagram. We report the magnetic properties of 36% Mn doped single-crystalline Sr₃(Ru_1-xMn_x)₂O₇ (x = 0.36). The temperature dependence of the zero-field cooled magnetic susceptibility shows a significant downturn akin to the collective freezing of the spins below a freezing temperature T_f, which is suppressed by the applied magnetic field. The onset of the spin freezing is accompanied by the development of large magnetic memory, magnetic relaxation, and exchange bias effects, which suggests Sr₃(Ru_0.64Mn_0.36)₂O₇ has the spin glass (SG) ground state. Further analysis reveals the presence of de Almeida-Thouless phase line separating the high temperature paramagnetic (PM) and low temperature SG phases with T_SG ~ 32 K. The nature of the SG state and its implication will be discussed.