Vertical strain tuning and perpendicular magnetic anisotropy in La0.5Ca0.5MnO3 vertically aligned nanostructured thin films by the application of high magnetic fields

Abstract

Epitaxial La0.5Ca0.5MnO3 (LCMO) thin films with vertically aligned nanostructures (VANs) have been achieved with the application of high magnetic fields in pulsed laser deposition processing. More interestingly, the microstructures, vertical strain, and perpendicular magnetic anisotropy (PMA) in the LCMO VAN films can be systematically manipulated by changing the applied high magnetic field strength. With increasing the high magnetic field, an increase in growth rate and a decrease in nanocolumn dimension are observed in the LCMO VAN films, which can be attributed to the enhanced suppression effect on adatom mobility and surface diffusion. Different from the LCMO planar-structured films, the intrinsic stress behaviors associated with vertical interfaces and grain boundaries instead of substrate strain in the LCMO VAN films are dominant in vertical strain evolution, indicating an out-of-plane compressive state, which is highly correlated with the growth rate and nanocolumn dimension. A core-shell model based on phase separation is proposed to understand the nanoscale size effect on magnetic properties in the LCMO VAN films. A tunable and enhanced PMA effect in the LCMO VAN films is also demonstrated. The results suggest that the application of a high magnetic field in pulsed laser deposition processing is a practicable route to achieve tunable VANs, and manipulate physical properties in manganite films.