We report x-ray resonant magnetic scattering (XRMS) and resonant inelastic x-ray scattering (RIXS) studies of epitaxially-strained Sr2IrO4 thin films. The films were grown on SrTiO3 and (LaAlO3)0.3(Sr2AlTaO6)0.7 substrates, under slight tensile and compressive strains, respectively. Although the films develop a magnetic structure reminiscent of bulk Sr2IrO4, the magnetic correlations are extremely anisotropic, with in-plane correlation lengths significantly longer than the out-of-plane correlation lengths. In addition, the compressive (tensile) strain serves to suppress (enhance) the magnetic ordering temperature TN, while raising (lowering) the energy of the zone boundary magnon. Quantum chemical calculations show that the tuning of magnetic energy scales can be understood in terms of strain-induced change in bond lengths.
@article{arxiv.1312.4005,
title = {Tuning Magnetic Coupling in Sr$_2$IrO$_4$ Thin Films with Epitaxial Strain},
author = {A. Lupascu and J. P. Clancy and H. Gretarsson and Zixin Nie and J. Nichols and J. Terzic and G. Cao and S. S. A. Seo and Z. Islam and M. H. Upton and Jungho Kim and A. H. Said and D. Casa and T. Gog and Vamshi M. Katukuri and H. Stoll and L. Hozoi and J. van den Brink and Young-June Kim},
journal= {arXiv preprint arXiv:1312.4005},
year = {2014}
}