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Defect-induced, temperature-independent, tunable magnetoresistance of partially fluorinated graphene foam

Rehman Sagar, Rizwan Ur, Shehzad, Khurram, Ali, Ayaz, Stadler, Florian J., Khan, Qasim, Zhao, Jingjing, Wang, Xiaohao, Zhang, Min
Carbon 2019 v.143 pp. 179-188
ambient temperature, foams, graphene, magnetic fields
The magnetoresistance (MR) of graphene is fixed under a particular magnetic field and temperature but can be further improved or controlled by introducing artificial defect states. These artificial defects can be introduced via fluorination, which is a conventional method to control the magnitude of the MR required for magnetoelectronic applications. One of the main benefits of fluorination is the defluorination, which occurs within a few days. Herein, tunable and temperature-independent magnetotransport of graphene foam (GF) is achieved using a controlled fluorination process. The magnitude of the MR decreases with the increasing fluorination time (i.e., 30, 60 and 90 min), indicating that defect-induced scattering plays a major role in the magnetotransport properties of fluorinated GF (FGF). The magnitude of the MR in the FGF specimens at room temperature (under a magnetic field strength of 5 T) was observed for three months; a particular value of the MR (FGF-30–59%, FGF-60–58%, FGF-90–37%) is observed that is higher in magnitude than that on the first day of fluorination. In this way, fluorination of GF can provide a pathway to tune the magnetotransport properties, which is very useful for magnetoelectronics devices, especially highly sensitive magnetic sensors.