▎ 摘　　要

Study of electron transport in chemically synthesized graphene (CSG) under magnetic field and its magnetization due to the presence of a transition-metal (TM) atom on its surface is indeed an interesting area of research in condensed-matter physics. In the last few years, several theoretical along with a few experimental results have been reported on magnetotransport in CSG, however the interaction of conduction electrons with the induced magnetic moments arising due to charge-transfer effect when a TM atom is placed on the CSG surface is poorly understood. In the present paper, CSG has been decorated by dilute concentration of the TM (Ni, Co) atom to investigate the interaction of the conduction electron and induced magnetic moment in CSG due to the presence of the TM atom and their effect on overall magnetotransport behavior. Large positive magnetoresistance (MR) is obtained in CSG over the entire temperature and field range, however in the case of TM decorated CSG (TM-CSG) a dramatic change in MR (from positive to negative) is observed in the high-field region after 30 K. The positive MR in CSG arises due to wave-function shrinkage and the large negative MR is explained in TM-CSG by the electron-hole (e-h) puddle generated in CSG due to charge impurity and disorder created due to the presence of the TM atom on the CSG surface. A magnetic hysteresis loop up to 5 K also confirms the magnetic moment generated in CSG as a result of charge transfer from the TM atom to CSG.