Effect of shell ratio on Mn/Co2+/3+ cation distribution and exchange anisotropy behavior in spinel interphase supported Mn2O3-Co3O4 nanostructures

This study demonstrates a strategy for designing and manufacturing a novel core-shell Mn2O3-Co3O4 nanostructure for significantly enhanced exchange anisotropy or exchange bias (EB) properties via a two-step seeded growth mechanism. The modified chemical route establishes cation exchange between Mn2+/3+ and Co2+/3+ ions, forming a novel interphase, i.e., CoMn2O4, which serves as an efficient channel for altering the physical properties of the prepared nanostructures. Here, we provided experimental evidence of interphase driven magnetic and EB attributes in Mn2O3-Co3O4. Structural and morphological results asserted three distinct phases within the core-shell-like morphology. Furthermore, the CoMn2O4 interface-enabled modified cationic distribution was investigated through XPS, which indicated the preferable cationic arrangements as Co3+Mn2+Mn3+O8-. Magnetic results unveil a strong ferrimagnetic (FIM) contribution within antiferromagnetic (AFM) regions, resulting in large thermomagnetic irreversibility below the blocking temperature. Effective AFM/FIM coupling generates exchange anisotropy, and results in enormous EB that exhibits a proportional dependence on the CoMn2O4 phase. The training effect in terms of field cycle variation was also investigated and fitted with a thermal relaxation model. The remarkable EB and coercivity (HC) values, accompanied by nearly no training effect, advocate the resilience and superiority of these compounds in the technological realms of magnetic memory devices and spintronics applications.