Competing incommensurate spin fluctuations and magnetic excitations in infinite-layer nickelate superconductors

The discovery of superconductivity in doped infinite-layer nickelates has recently garnered significant attention. Here, the authors employed a quantum many-body Green's function-based approach to investigate the electronic and magnetic fluctuations in LaNiO2 providing microscopic insight into the origin of suppressed long-range order and magnetic excitation spectrum in the nickelates, along with their potential correlation with the cuprates. The recently discovered infinite-layer nickelates show great promise in helping to disentangle the various cooperative mechanisms responsible for high-temperature superconductivity. However, lack of antiferromagnetic order in the pristine nickelates presents a challenge for connecting the physics of the cuprates and nickelates. Here, by using a quantum many-body Green's function-based approach to treat the electronic and magnetic structures, we unveil the presence of many two- and three-dimensional magnetic stripe instabilities that are shown to persist across the phase diagram of LaNiO2. Our analysis indicates that the magnetic properties of the infinite-layer nickelates are closer to those of the doped cuprates, which host a stripe ground state, rather than the undoped cuprates. The computed longitudinal-spin, transverse-spin, and charge spectra of LaNiO2 are found to contain an admixture of contributions from localized and itinerant carriers. Theoretically obtained dispersion of magnetic excitations (spin-flip) is found to be in good accord with the results of recent resonant inelastic X-ray scattering experiments. Our study gives insight into the origin of strong magnetic competition in the infinite-layer nickelates and their relationship with the cuprates.