Spontaneous Faraday rotation of $${\text{C}\text{o}}_{x}{\text{F}\text{e}}_{3-x}{\text{O}}_{4}$$ thin films electrodeposited under a static magnetic field

Abstract

$${\text{C}\text{o}}_{x}{\text{F}\text{e}}_{3-x}{\text{O}}_{4}$$ ( $$0<x\le 1)$$ thin films were elaborated by electrodeposition under a static magnetic field on fluorine-doped tin oxide (FTO) substrates followed by an air annealing at 500 °C for 24 h. The XRD analysis revealed cubic spinel structure with an average crystallite size ranging from 40 to 46 nm. Moreover, the SEM and AFM observations indicated a noticeable magnetic field effect on the surface morphology. The optical band gap deduced from the transmittance data is around 3.4 eV. The magneto-optical measurements indicated very interesting spontaneous Faraday rotation of $$4628^{\circ}/\text{c}\text{m}$$ . The successful elaboration of partially hard magnetic cobalt ferrite thin films offers a new route for high potential exploitation of the spontaneous Faraday rotation effect, which is necessary to develop advanced and miniaturized non-reciprocal optical devices.