  Flat-band physics has attracted much attention in recently years because of
its interesting properties and important applications. Some typical lattices
have been proposed to generate flat bands, such as Kagome and Lieb lattices.
The flat bands in these lattices contact with other bands rather than isolated.
However, an ideal flat band should be isolated, because isolation is a
prerequisite for a number of important applications. Here, we propose a new
lattice that can produce isolated flat bands. The lattice is named as
interlocking-circles lattice because its pattern seems like interlocking
circles. Moreover, the new lattice is realized in graphene by hydrogenation. In
the hydrogenated graphene, there are two nontrivial isolated flat bands
appearing around the Fermi level. Upon hole or electron doping, the flat bands
split into spin-polarized bands and then result in a ferromagnetic graphene.
Our work not only proposes a new type of lattice but also opens a way to find
systems with isolated flat bands.
