Enhanced magnetoelectric coupling in vertically aligned nanocomposite thin films via ferroelectric capping layer encapsulation

Abstract

Vertically aligned nanocomposite (VAN) thin films with strong magnetoelectric (ME) coupling and high magnetic anisotropy are promising for next-generation low-power storage devices. However, conventional self-assembled VANs often exhibit incomplete ME coupling due to exposed ferromagnetic (FM) phases above the ferroelectric (FE) matrix surface, which limits the strain-mediated interactions. Here, we propose a FE capping layer strategy to encapsulate exposed FM phases in VANs. This design not only increases perpendicular magnetic anisotropy from 3.08 × 104 to 9.49 × 104 J m−3 but also significantly improves both direct and converse ME coupling. The direct ME (DME) coefficient rises from 80 to 216 mV cm−1 Oe−1, while the converse ME coefficient increases from 6.32 × 10−10 to 8.17 × 10−10 s m−1, attributed to restored interfacial strain coupling. This work demonstrates that the encapsulation of FM phase by FE capping layer optimizes ME performance in VANs, offering a viable route for high-density magnetoelectronic applications.