We extend the concept of conventional multiferroicity  -- where ferroelectric and ferromagnetic orders coexist -- to include multipolar degrees of freedom. Specifically, we explore how this phenomenon emerges in 4d²/5d² Mott insulators with strong spin-orbit and Hund's couplings. Our study uncovers the origin of magnetic multipolar interactions in these systems and demonstrates that a combination of quadrupolar and octupolar magnetic order can simultaneously induce both electrical quadrupolar moments and ferroelectric polarization. By expanding the multiferroic framework to higher-order multipoles, we reveal the possibility of coexisting multipolar orders of different or same ranks, paving the way for new functional properties in a large class of strongly correlated materials.

References: 

arXiv:2408.17389 (2025)