Polyaniline Functionalized Magnetic Fe3O4/MXene Composites with Tunable Negative Organic Magnetoresistance

Polymer composites with room temperature magnetoresistance (MR) are attractive for emerging magnetic sensors and information-storage devices in the era of the Internet of Things. In this work, the magnetorsistive polyaniline (PANI) functionalized magnetic Ti 3 C 2 T x Composites were prepared by solvothermal and in-situ polymerization method. By decorating non-magnetic Ti 3 C 2 T x with magnetic Fe 3 O 4 particles and tuning the Fe 3 O 4 loading on Ti 3 C 2 T x , the room temperature magnetoresistance can be effectively controlled. The Ti 3 C 2 T x /PANI (T/P) composites exhibit positive MR of 4.65% at 2 T, while the Fe 3 O 4 –Ti 3 C 2 T x /PANI (FT/P) composites demonstrates negative MR of -11.13% at 2 T with 60 wt% Fe 3 O 4 loading in Fe 3 O 4 –Ti 3 C 2 T x . Structural and morphological characterizations (SEM, TEM, XRD, FT-IR and XPS) confirm the successful fabrication of FT/P composites. The positive MR in T/P is well described by the wave-function shrinkage model, and the negative MR in FT/P composites is quantitatively fitted by the forward interference model. The localization length ( a 0 ), hopping distance (R hop ) and density of states at the Fermi level (N(E F )) are evaluated. The localization length decreases with increasing magnetic field for all samples and is significantly larger in T/P than in FT/P composites. This work demonstrates a simple and effective strategy to achieve tunable negative MR at room temperature PANI composites for magnetic sensing and data-storage applications.