  We point out the generic competition between the Hund's coupling and the
spin-orbit coupling in correlated materials, and this competition leads to an
electronic dilemma between the Hund's metal and the relativistic insulators.
Hund's metals refer to the fate of the would-be insulators where the Hund's
coupling suppresses the correlation and drives the systems into correlated
metals. Relativistic Mott insulators refer to the fate of the would-be metals
where the relativistic spin-orbit coupling enhances the correlation and drives
the systems into Mott insulators. These contradictory trends are naturally
present in many correlated materials. We study the competition between Hund's
coupling and spin-orbit coupling in correlated materials and explore the
interplay and the balance from these two contradictory trends. The system can
become a spin-orbit-coupled Hund's metal or a Hund's assisted relativistic Mott
insulator. Our observation could find a broad application and relevance to many
correlated materials with multiple orbitals.
