  The magnetic glassy state is a fascinating phenomenon, which results from the
kinetic arrest of the first order magnetic phase transition. Interesting
properties, such as metastable magnetization and nonequilibrium magnetic
phases, are naturally developed in the magnetic glassy state. Here, we report
magnetic glass property in the low spin state of Co3+ in EuBaCo2O5+{\delta}
({\delta} = 0.47) cobaltite at low temperature (T < 60 K). The measurements of
magnetization under the cooling and heating in unequal fields, magnetization
relaxation and thermal cycling of magnetization show the kinetic arrest of low
magnetization state below 60 K. The kinetically arrested low temperature
magnetic phase is further supported through the study of isothermal magnetic
entropy, which shows the significant entropy change. The present results will
open a new window to search the microscopic relation between the spin state
transitions and the kinetic arrest induced magnetic glassy phenomena in complex
materials.
