  The interaction between microscopic particles has always been a fascinating
and intriguing area of science. Direct interrogation of such interactions is
often difficult or impossible. Structured electromagnetic systems offer a rich
toolkit for mimicking and reproducing the key dynamics that governs the
microscopic interactions, and thus provide an avenue to explore and interpret
the microscopic phenomena. In particular, metamaterials offer the freedom to
artificially tailor light-matter coupling and to control the interaction
between unit cells in the metamaterial array. Here we demonstrate a terahertz
metamaterial that mimics spin-related interactions of microscopic particles in
a 2D lattice via complex electromagnetic multipole interactions within the
metamaterial array. Fano resonances featured by distinct mode properties due to
strong nearest-neighbor interactions are discussed that draw parallels with the
2D Ising model. Interestingly, a hyperfine Fano splitting spectrum is observed
by manipulating the 2D interactions without applying external magnetic or
electric fields, which provides a passive multispectral platform for
applications in super-resolution imaging, biosensing, and selective thermal
emission. The dynamic approach to reproduce the static interaction between
microscopic particles would enable more profound significance in exploring the
unknown physical world by the macroscopic analogues.
