  The temperature ($T$) - magnetic field ($H$) phase diagram for the tetragonal
layered compound CeSbSe, is determined from magnetization, specific heat, and
electrical resistivity measurements. This system exhibits complex magnetic
ordering at $T_{\rm{M}}$ $=$ 3 K and the application of a magnetic field
results in a cascade of magnetically ordered states for $H$ $\lesssim$ 1.8 T
which are characterized by fractional integer size steps: i.e., a possible
Devil's staircase is observed. Electrical transport measurements show a weak
temperature dependence and large residual resistivity which suggest a small
charge carrier density and strong scattering from the $f$-moments. These
features reveal Kondo lattice behavior where the $f$-moments are incompletely
screened, resulting in a fine balanced magnetic interaction between different
Ce neighbors that is mediated by the RKKY interaction. This produces the nearly
degenerate magnetically ordered states that are accessed under an applied
magnetic field.
