Magnetodielectric and TMR effects in P(VDF-HFP)/SrFe12O19 composite films for magnetic field – Tuned photodetector application

Abstract

Magnetoelectric (ME) multiferroic materials possess extensive research interest as a result of their use in a variety of sectors. In this work, the optical properties of plain P(VDF-HFP) film and P(VDF-HFP)/SrFe12O19 composite films are investigated through UV-Vis absorption spectroscopy. In addition, the ME coupling of SrFe12O19 nanofibers reinforced P(VDF-HFP) composite films is investigated though magnetodielectric (MD) measurements. The parameters such as dielectric constant, capacitance, dielectric loss and impedance of the composite films are found to change with the applied magnetic field which is attributed to the direct ME coupling of the composite films. The prepared ME films show a negative tunneling magnetoresistance (TMR) effect with maximum TMR% of 14 % for the film (PSNF20) with 20 wt% of SrFe12O19 nanofiber loading. Photodetectors are fabricated using the films as active elements and the performance of the photodetectors is studied under various intensities of visible light radiation. All the devices exhibit good photosensitivity, responsivity and specific detectivity at an illumination intensity of 20 mW/cm2. The photodetector (PD20) fabricated using PSNF20 as an active element has the maximum rise/decay time, photosensitivity, responsivity and specific detectivity values as 468 /553 ms, 2.7 × 103, 22 mA/W and 6.77 × 1013 Jones, respectively at 20 mW/cm2. In addition, the performance of the devices is analyzed by subjecting the active element to external magnetic field. The photosensitivity, responsivity and specific detectivity all improve, showing that the magnetic field has an effect on the photodetector. The above parameters are maximum for PD20 device and the values are 4.3 × 103, 26 mA/W and, 8.01 × 1013 Jones, respectively at 4000 Oe and 20 mW/cm2. Thus, the prepared flexible magnetoelectric films of P(VDF-HFP)/SrFe12O19 nanofiber composites have been shown to be good options for the magnetic field tuned photodetector applications such as environmental sensing monitor, safety and security, optical communication systems, magnetic sensors, piezoelectric sensors and spintronics devices.