We report on the tuning of magnetic interactions in superlattices composed of single and bilayer SrIrO3 inter-spaced with SrTiO3. Magnetic scattering shows predominately c-axis antiferromagnetic orientation of the magnetic moments for the bilayer justifying these systems as viable artificial analogues of the bulk Ruddlesden-Popper series iridates. Magnon gaps are observed in both superlattices, with the magnitude of the gap in the bilayer being reduced to nearly half that in its bulk structural analogue, Sr3Ir2O7. We assign this to modifications in the anisotropic exchange driven by bending of the c-axis Ir-O-Ir bond and subsequent local environment changes, as detected by x-ray diffraction and modeled using spin wave theory. These findings explain how even subtle structural modulations driven by heterostructuring in iridates are leveraged by spin orbit coupling to drive large changes in the magnetic interactions.
@article{arxiv.1707.08910,
title = {Magnetism in artificial Ruddlesden-Popper iridates leveraged by structural distortions},
author = {D. Meyers and Yue Cao and G. Fabbris and Neil J. Robinson and Lin Hao and C. Frederick and N. Traynor and J. Yang and Jiaqi Lin and M. H. Upton and D. Casa and Jong-Woo Kim and T. Gog and E. Karapetrova and Yongseong Choi and D. Haskel and P. J. Ryan and Lukas Horak and X. Liu and Jian Liu and M. P. M. Dean},
journal= {arXiv preprint arXiv:1707.08910},
year = {2019}
}