Abstrakt
A fundamental difference between antiferromagnets and ferromagnets is the lack of linear coupling to a uniform magnetic field due to the staggered order parameter(1). Such coupling is possible via the Dzyaloshinskii-Moriya (DM) interaction(2,3), but at the expense of reduced antiferromagnetic (AFM) susceptibility due to the canting-induced spin anisotropy(4).
We solve this long-standing problem with a top-down approach that utilizes spin-orbit coupling in the presence of a hidden SU(2) symmetry. We demonstrate giant AFM responses to sub-tesla external fields by exploiting the extremely strong two-dimensional critical fluctuations preserved under a symmetry-invariant exchange anisotropy, which is built into a square lattice artificially synthesized as a superlattice of SrIrO3 and SrTiO3.
The observed field-induced logarithmic increase of the ordering temperature enables highly efficient control of the AFM order. Our results demonstrate that symmetry can be exploited in spin-orbit-coupled magnets to develop functional AFM materials for fast and secured spintronic devices(5-9).