  We study theoretically spin excitations in the newly discovered nickelate
superconductors based on a single-band model and the random phase
approximation. The spin excitations are found to be incommensurate in a low
energy region. A spin resonance phenomena is revealed as the excitation energy
increases. The maximum intensity may be at the incommensurate momentum or the
commensurate momentum, depending on the out-of-plane momentum. The spin
excitations become incommensurate again at higher energies. The similarities
and differences of the spin excitations between nickelate and cuprate
superconductors are addressed. Our predicted results can be tested by inelastic
neutron scattering experiments later.
