Supplementary Material

The supplementary material contains the cross sectional FESEM images (Fig. S1), XPS 2p spectra along with the detailed analysis of the chemical state (Fig. S2) and KPFM scans (Fig. S3) of the grown Fe3O4 batches. The MR measurement of top Co electrode has been presented in Fig. S4. The structural, microstructural details and valence band spectra of the PVDF thins films extracted from AFM and GI-XRD, KPFM and XPS measurements are shown in Fig. S5, Fig. S6 & Fig. S8. The spin-transport measurements of FFB 80, FFB 120 and FFB 230 devices are presented in Fig. S7.