Abstract
The field of opto-spintronics, which is basically an interaction between photon and spin-dependent carrier transport, bears an attractive role in the direction of next-generation advanced multifunctional storage and ultra-fast modern photo sensor technology. The effect of Opto-spintronics can be achieved by two distinct approaches; in one hand, it can be achieved by tuning of optical response under applied magnetic field, and another hand, magnetic field response can be modulated by optical power. Here, a comparative study on both optical power-dependent AC impedance spectroscopy under different applied magnetic fields, and optical power-modulated magnetoimpedance properties has been carried out in two hybrid inorganic/organic heterojunctions: Si/NiFe₂O₄/P3HT/CuPc/Al (S1) and Si/ NiFe₂O₄/rGO/CuPc/Al (S2). Nickel ferrite NiFe₂O₄ act as a magnetic layer, whereas poly(3-hexylthiophene) (P3HT) and reduced graphene oxide (rGO) act as organic and carbon-based interfacial opto-electronic layers, respectively. Impedance vs frequency curves exhibit two distinct relaxation peaks in S1 heterojunction, whereas in case of S2 device a single relaxation peak is observed. Magnetoimpedance under light illumination conditions also reveals distinct behaviour. The magnetoimpedance properties under magneto-optical coupling response also reveal distinct behaviour. In P3HT-based heterojunction, magnetoimpedance increases from -58% to -76% under strong illumination of 660 nm red laser light and 3 kOe magnetic field, attributing enhanced photo-carrier density at the NFO/P3HT interface. In contrast, the rGO spacer layer-based device shows a reduction of magneto-impedance under similar conditions, attributed to pronounced scattering of photocarriers at the NFO/rGO interface. This comparative study on Impedance spectroscopy highlights potential of interface engineering for multifunctional device applications.
Biography
Currently, Nitish Ghosh is pursuing a PhD under the supervision of Dr. Puja Dey, under a UGC-SRF fellowship (Government of India) at the Department of Physics, Kazi Nazrul University, West Bengal. His PhD thesis is expected to be submitted by January 2026. He has published more than 10 papers in reputed journals and filed one patent application. His area of research interest is as follows: (a) Organic Spintronics; (b) Opto-Spintronics; (c) Organic Photodetector; (d) Multifunctional Nanostructured Oxides and heterostructure; (e) Ultra-thin Ferromagnetic film.
