Large off-diagonal magnetoelectricity in a triangular Co2+-based collinear antiferromagnet.

Magnetic toroidicity is an uncommon type of magnetic structure in solid-state materials. Here, we experimentally demonstrate that collinear spins in a material with R-3 lattice symmetry can host a significant magnetic toroidicity, even parallel to the ordered spins. Taking advantage of a single crystal sample of CoTe₆O₁₃ with an R-3 space group and a Co²⁺ triangular sublattice, temperature-dependent magnetic, thermodynamic, and neutron diffraction results reveal A-type antiferromagnetic order below 19.5 K, with magnetic point group -3′ and k = (0,0,0). Our symmetry analysis suggests that the missing mirror symmetry in the lattice could lead to the local spin canting for a toroidal moment along the c axis. Experimentally, we observe a large off-diagonal magnetoelectric coefficient of 41.2 ps/m that evidences the magnetic toroidicity. In addition, the paramagnetic state exhibits a large effective moment per Co²⁺, indicating that the magnetic moment in CoTe₆O₁₃ has a significant orbital contribution. CoTe₆O₁₃ embodies an excellent opportunity for the study of next-generation functional magnetoelectric materials.Magnetoelectric coupling, where magnetic and electronic order is linked, allows for the control of magnetism via an electric field and vice versa, potentially offering new approaches to data storage, sensors, actuators and wealth of other devices. Here, using a diverse array of experimental probes, Xu et al show the emergence of both diagonal and off-diagonal magnetoelectric coupling in CoTe₆O₁₃. [ABSTRACT FROM AUTHOR]