Abstract
We report an experimental investigation of the two-dimensional antiferromagnetic Mott insulator by varying the interlayer exchange coupling in [, ] (, 2 and 3) superlattices. Although all samples exhibited an insulating ground state with long-range magnetic order, temperature-dependent resistivity measurements showed a stronger insulating behavior in the and samples than the sample which displayed a clear kink at the magnetic transition. This difference indicates that the blocking effect of the excessive layer enhances the effective electron-electron correlation and strengthens the Mott phase. The significant reduction of the Néel temperature from 150 K for to 40 K for demonstrates that the long-range order stability in the former is boosted by a substantial interlayer exchange coupling. Resonant x-ray magnetic scattering revealed that the interlayer exchange coupling has a switchable sign, depending on the layer number , for maintaining canting-induced weak ferromagnetism. The nearly unaltered transition temperature between the and the demonstrated that we have realized a two-dimensional antiferromagnet at finite temperatures with diminishing interlayer exchange coupling.
- Received 29 January 2017
DOI:https://doi.org/10.1103/PhysRevLett.119.027204
© 2017 American Physical Society