Thermal relaxation in charge ordered $Pr_{0.63}Ca_{0.37}MnO_3$ in the presence of a magnetic field

We report the observation of substantial thermal relaxation in a single crystal of the charge ordered system $Pr_{0.63}Ca_{0.37}MnO_3$ in an applied magnetic field of H=8 T. The relaxation is observed when the temperature is scanned in the presence of a magnetic field in the temperature interval $T_{MH}<T<T_{CO}$, where $T_{CO}$ is the charge ordering temperature and $T_{MH}$ is the charge melting temperature in a field. In this temperature range, the system has coexisting charged ordered insulator (COI) and ferromagnetic metallic (FMM) phases. No such relaxation is observed in the COI state in H=0 T or in the FMM phase at $T