Strain-insensitive ferromagnetic SrRuO₃ thin films with ferrimagnetic CoFe₂O₄ buffer layer

Flexible electronics, such as wearable devices and biosensors, require materials that maintain their properties under mechanical stress. A recent study addresses this by focusing on SrRuO₃ (SRO) thin films, which typically suffer reduced coercivity under strain. Herein, we introduce a novel approach by using CoFe₂O₄ (CFO) as a buffer layer in SRO/CFO/F-mica heterostructures to address this issue. When subjected to a strain of up to ±0.553 %, these heterostructures displayed a mere 11 % variation in saturation magnetic moment and coercive field, significantly outperforming SRO/BaTiO₃ configurations, which showed a 95 % reduction in coercivity at only −0.3 % strain. This result demonstrates the effectiveness of the CFO layer in stabilizing the magnetic properties of SRO films against external mechanical deformations. These findings mark a significant advancement in the development of mechanically robust thin films for complex oxide heterostructures in flexible device applications.