Eu0.5Sr1.5MnO4: A three-dimensionalXYspin glass

The frequency, temperature, and dc-bias dependence of the ac susceptibility of a high-quality single crystal of the ${\mathrm{Eu}}_{0.5}{\mathrm{Sr}}_{1.5}\mathrm{Mn}{\mathrm{O}}_4$ layered manganite is investigated. ${\mathrm{Eu}}_{0.5}{\mathrm{Sr}}_{1.5}\mathrm{Mn}{\mathrm{O}}_4$ behaves like an $XY$ spin glass with a strong basal anisotropy. Dynamical and static scalings reveal a three dimensional phase transition near $T_g=18\mathrm{K}$ and yield critical exponent values between those of Heisenberg- and Ising-like systems, albeit slightly closer to the Ising case. Interestingly, as in the latter system, the here-observed rejuvenation effects are rather weak. The origin and nature of the low-temperature $XY$ spin glass state are discussed.