Unified Terahertz Framework for Magnetic and Lattice Responses Reveals an Elusive Ordering Transition in Gd$_2$Ru$_2$O$_7$

Magnetic order in materials combining localized rare-earth moments with itinerant transition-metal sublattices generates internal fields whose lattice imprint is rarely accessed directly.

Magnetic order in materials combining localized rare-earth moments with itinerant transition-metal sublattices generates internal fields whose lattice imprint is rarely accessed directly. In Gd pyrochlore ruthenate, we find that a single terahertz spectrum resolves an…