Magnetic behavior, Griffiths phase and magneto-transport study in 3d based nano-crystalline double perovskite Pr₂CoMnO₆

Double perovskite (DP) oxide material receive extensive research interest due to exciting physical properties with potential technological application. 3$d$ based DP oxides are promising for exciting physics like magnetodielectric, ferroelectric, Griffith phase etc., specially Co/Mn DPs are gaining much research interest. In this paper we present the study of magnetic phase and transport properties in nano-crystalline Pr$_2$CoMnO$_6$ a 3$d$ based double perovskite compound. This material shows a paramagnetic (PM) to ferromagnetic (FM) phase transition below 173 K marked by a rapid increase in magnetic moment due to spin ordering. We found divergence in inverse magnetic susceptibility ($\chi$$^{-1}$) from Curie weiss behavior around 206 K which indicates the evolution of Griffiths phase before actual PM-FM transition. We found that the Griffiths phase suppressed with increasing applied magnetic filed. For the understanding of charge transport in this material we have measured temperature dependent electrical resistivity. Pr$_2$CoMnO$_6$ is a strong insulator where resistivity increase abruptly below magnetic phase transition. To understand the effect of magnetic field on transport behavior we have also measured the magnetoresistance (MR) at different temperatures. Sample shows the negative MR with maximum value $\sim$22 $\%$ under applied magnetic field of 50 kOe at 125 K. MR follows quadratic field dependency above $T_c$ however below $T_c$ the MR shows deviation from this field dependency at low field.