Phase transition in La0.6Sr0.4CoO3-δ thin films by ion irradiation

Perovskite oxides exhibit rich physics related to ionic defects. In particular, the defect concentration and distribution alter the lattice parameters and affect the competitive interplay between strongly correlated electrons, enabling numerous applications as sensors, catalysts, and memristive devices. In this work, helium-ion irradiation is demonstrated as an effective, low-temperature tool to modulate the vacancy profiles in epitaxial La0.6Sr0.4CoO3-δ thin films. A significant lattice expansion solely along the out-of-plane direction is observed. By proper tuning of the irradiation parameters, the resistivity is increased up to several orders of magnitude. These results offer a new playground for optimizing oxide-based spintronic and electronic devices.