Achieving an efficient control of antiferromagnetic order in artificial layered iridates

Antiferromagnetic (AFM) materials started to gain traction owing the advantages of reliability, ultrafast dynamics, etc. in spintronic applications. In our recent work, we investigated AFM order in layered iridates, which is a newly established Mott system similar to cuprates but features a strong spin-orbit coupling. By building the spin-orbit Mott insulators as SrIrO₃/SrTiO₃ superlattices, we gained controllability in the strength and sign of interlayer exchange interaction. This enables one to reach the 2D limit of a magnet, where the ordering temperature is only governed by magnetic anisotropy. The 2D antiferromagnet preserves a hidden SU(2) symmetry, which was first proposed in cuprates but never experimentally realized. Specifically, we unveiled that Dzyaloshinskii-Moriya interaction in the square-lattice magnet does not contribute to the spin anisotropy. The extremely strong 2D critical fluctuations enable us to achieve giant AFM responses to sub-tesla magnetic fields. The observed field-induced logarithmic increase of the AFM ordering demonstrates a new pathway for designing efficient AFM spintronics. These results were recently published on Phys. Rev. Lett. [119,027204, (2017)] and Nat. phys. [14, 806--810 (2018)].