  Nodal loop appears when two bands, typically one electron-like and one
hole-like, are crossing each other linearly along a one-dimensional manifold in
the reciprocal space. Here we propose a new type of nodal loop which emerges
from crossing between two bands which are both electron-like (or hole-like)
along certain direction. Close to any point on such loop (dubbed as a type-II
nodal loop), the linear spectrum is strongly tilted and tipped over along one
transverse direction, leading to marked differences in magnetic, optical, and
transport responses compared with the conventional (type-I) nodal loops. We
show that the compound K4P3 is an example that hosts a pair of type-II nodal
loops close to the Fermi level. Each loop traverses the whole Brillouin zone,
hence can only be annihilated in pair when symmetry is preserved. The symmetry
and topological protections of the loops as well as the associated surface
states are discussed.
