  The combination of different exotic properties in materials paves the way for
the emergence of their new potential applications. An example is the recently
found coexistence of the mutually antagonistic ferromagnetism and
superconductivity in hydrogenated boron-doped diamond, which promises to be an
attractive system with which to explore unconventional physics. Here, we show
the emergence of Yu-Shiba-Rusinov (YSR) bands with a spatial extent of tens of
nanometers in ferromagnetic superconducting diamond using scanning tunneling
spectroscopy. We demonstrate theoretically how a two-dimensional (2D) spin
lattice at the surface of a three-dimensional (3D) superconductor gives rise to
the YSR bands, and how their density-of-states profile correlates with the spin
lattice structure. The established strategy to realize new forms of the
coexistence of ferromagnetism and superconductivity opens a way to engineer the
unusual electronic states and also to design better performing superconducting
devices.
