Electronic correlation-driven exotic quantum phase transitions in infinite-layer manganese oxide

Despite the intensive interest in copper-and nickel-based superconductivity in infinite-layer structures, the physical properties of many other infinite-layer transition-metal oxides remain largely unknown. Here we unveil, by the first-principles calculations, the electronic correlation (EC)-driven series of quantum-phase transitions (QPTs) in infinite-layer SrMnO2, where spin and charge orders are strongly interwoven. At a weak EC region, SrMnO2 is a ferromagnetic metal with anisotropic spin transportation, as a promising spin valve under room temperature. When EC is slightly increased, a structural transition accompanied by charge/bond disproportion occurs as a consequence of Fermi surface nesting, resulting in a ferromagnetic insulator with reduced Curie temperature. When EC is further enhanced, another structural transition occurs that drives the system into a different-type multiferroic phase with piezoelectricity-tunable antiferromagnetic orders. Therefore, infinite-layer SrMnO2 is possibly a unique system on the quantum critical point, where small perturbations of EC can realize a series of QPTs.