Supercritical CO2-induced strain in PbTiO3 to realize room-temperature ferromagnetism

Abstract

The development of two-dimensional ferromagnetic materials is of great significance for the next generation of spintronic devices. This work proposes an innovative strategy based on supercritical carbon dioxide (SC CO₂)-assisted lattice strain engineering, which successfully achieves room-temperature ferromagnetism in two-dimensional PbTiO₃ nanosheets. Through SC CO₂ induced in situ reactions, a PbTiO₃/PbO heterointerface with significant lattice mismatch was constructed on the PbTiO₃ surface. Systematic characterization revealed that the interface strain caused tensile deformation of the PbTiO₃ lattice and local octahedral distortion, while introducing a certain concentration of oxygen vacancies and Ti³⁺ ions. This unique structural modification enables the material to exhibit distinct room-temperature ferromagnetism. This study not only provides new insights into the magnetic regulation of two-dimensional perovskite materials but also demonstrates the unique advantages of supercritical fluid technology in functional material design.