  Magnetic field effects on the one-dimensional frustrated ferromagnetic chain
are studied by means of effective field theory approaches in combination with
numerical calculations utilizing Lanczos diagonalization and the density matrix
renormalization group method. The nature of the ground state is shown to change
from a spin-density-wave region to a nematic-like one upon approaching the
saturation magnetization. The excitation spectrum is analyzed and the behavior
of the single spin-flip excitation gap is studied in detail, including the
emergent finite-size corrections.
