Low-energy plasmon excitations in infinite-layer nickelates

The discovery of superconductivity in infinite-layer nickelates is presently an important topic condensed-matter physics, and potential similarities to differences from cuprates are under intense debate. We determine general features the charge excitation spectrum two opposite viewpoints: (i) Nickelates regarded as strongly correlated electron systems like cuprate superconductors thus can be described by $t\text{\ensuremath{-}}J$ model, (ii) correlation effects not strong cuprates, thus, random-phase approximation (RPA) calculations may capture essential physics. find that both cases, plasmon excitations realized around momentum transfer $\mathbf{q}=(0,0,{q}_{z})$, although they tend damped more RPA. In particular, this damping enhanced relatively large interlayer hopping expected nickelates. Besides reproducing optical at $\mathbf{q}=(0,0,0)$ observed ${\mathrm{Nd}}_{0.8}{\mathrm{Sr}}_{0.2}{\mathrm{NiO}}_{2}$, we obtain low-energy plasmons with gaps $\ensuremath{\sim}360$ $\ensuremath{\sim}560$ meV $\mathbf{q}=(0,0,{q}_{z})$ for finite ${q}_{z}$ cases (ii), respectively. present work offers a possible theoretical hint answer whether cupratelike or contributes understanding dynamics