Effect of size, phase fraction and interface coupling on the magnetic behavior of al-modified α-Fe2O3/NiFe2O4 core–shell structure

• DOI: 10.1007/s00339-021-05135-y
• Publication Date: 2021-12-01T23:02:47Z
• Authors: S. Jena; D. K. Mishra; Shyamal Mondal; Sujay Chakravarty; Shamima Hussain; P. Mallick
• Keywords: 0103 physical sciences; 02 engineering and technology; 0210 nano-technology; 01 natural sciences

The effect of Al doping on the NiFe2O4 phase for the enhanced magnetic properties of α-Fe2O3/NiFe2O4 composite has been reported. The crystalline quality of the samples improves significantly with increasing Al doping concentration. The formation of core–shell structure in the samples along with the reduction in shell thickness with Al doping has been evidenced through morphological characterization. All the samples show the optical band gap value of 1.7 eV that could produce higher efficiency toward the visible light absorption. All the samples show the doubly inverted structure (TN > Tc). The low saturation magnetization and high coercivity in the Al-doped samples in comparison with the un-doped sample are observed because of the paramagnetic spin configuration of Al ions and interface coupling between α-Fe2O3 and NiFe2O4 phases. The different exchange coupling in Al-modified α-Fe2O3/NiFe2O4 composite systems could be associated with the NiFe2O4 phase. The occurrence of narrow band gap, ferromagnetism, loop shift, freezing temperature and doubly inverted structure in the nanocomposite samples could be beneficial for photo-electrochemical water splitting, photo-catalyst and magnetic memory device applications.