  Atomically thin ferromagnetic and conducting electron systems are highly
desired for spintronics, because they can be controlled with both magnetic and
electric fields. We present (SrRuO3)1-(SrTiO3)5 superlattices and
single-unit-cell-thick SrRuO3 samples that are capped with SrTiO3. We achieve
samples of exceptional quality. In these samples, the electron systems comprise
only a single RuO2 plane. We observe conductivity down to 50 mK, a
ferromagnetic state with a Curie temperature of 25 K, and signals of magnetism
persisting up to approximately 100 K.
