Interfacial coupling in heteroepitaxial vertically aligned nanocomposite thin films: From lateral to vertical control

• The lattice mismatch and strain engineering are discussed in VAN.
• Interfacial couplings are investigated in the vertical direction.
• The enhanced and tunable functionalities have been achieved and reviewed.
• Future directions and outlook for this field are proposed.

Very recently, vertically aligned nanocomposite (VAN) thin films have served as an intriguing platform to obtain significant insights of the fundamental physics and achieve novel functionalities for potential technological applications. In this review article, we have investigated the lattice mismatch and vertical interfacial coupling in representative VAN systems for probing strain engineering in the vertical direction. Systematic studies of ferroelectricity, low field magnetoresistance and magnetoelectric coupling in VAN architectures have been reviewed and compared. The enhancement and tunability of the physical properties are attributed to the effective strain-, phase- and interface- couplings in VAN films. In the end, important and promising research directions in this field are proposed, including understanding the growth mechanisms of VAN structures, and creating more effective couplings for enhanced functionalities and ultimate device applications.