Role of Magnetic Defects in Tuning Ground States of Magnetic Topological Insulators (Adv. Mater. 21/2023)

Magnetic Topological Insulators Inelastic neutron scattering measurements, as reported by Farhan Islam and co‐workers in article number 2209951, reveal the formation of linear Mn–Te–Mn antiferromagnetic dimers in Mn‐doped Sb2Te3 magnetic topological insulators, following the Goodenough–Kanamori superexchange rule. The experiments also identify ferromagnetic correlations within quintuple blocks and across the van der Waals gap, which mediate long‐range ferromagnetic order. These competing interactions explain the role of defects in tuning ground states in magnetic topological insulators.