Glassy magnetic ground state in La4/3Sr5/3Mn2O7: Role of first order phase transition and short range antiferromagnetic correlations.

We report the observation of reentrant spin glass state in the bilayered manganite with nominal composition La4/3Sr5/3Mn2O7. The studied compound transforms from a high temperature paramagnetic phase with antiferromagnetic type short range magnetic correlation to a ferromagnetic phase upon cooling. On further cooling, the long range ferromagnetic phase is destroyed leading to glassy magnetic phase. Our ac susceptibility analysis indicates the possibility of the existence of frozen spin clusters below the spin glass transition temperature. The cooling rate and cooling field dependence of magnetization measurements reveal that the glassy phase is closely connected with the arrested kinetics of the first order phase transition leading to the existence of antiferromagnetic/paramagnetic clusters along with the ferromagnetic phase at low temperature. [ABSTRACT FROM AUTHOR]