Motivated by the recent report on high Tc ferromagnetic insulating state of single transition metal containing double perovskite compound, Sr3OsO6 (Wakabayashi et. al., Nature Commun {\bf 10} 535, 2019), we study this curious behavior by employing first-principles calculations in conjunction with exact diagonalization of full t2g multiplet problem of two Os sites. Our analysis highlights the fact that stabilization of Sr3OsO6 in the cubic phase in epitaxially grown thin film is the key to both ferromagnetic correlation and high temperature scale associated to it. This also provides a natural explanation for the sister compound, Ca3OsO6 to exhibit low TN antiferromagnetism in its monoclinic structure. Further the insulating property is found to be driven by opening of Mott gap in the half filled spin-orbit coupled j=3/2 manifold of d2 Os. We point out that Sr2CaOsO6 which naturally forms in the cubic phase would be worthwhile to explore as a future candidate to exhibit high Tc ferromagnetic insulating state in bulk form.
@article{arxiv.2005.02582,
title = {Understanding the Curious Magnetic State of Sr$_{3}$OsO$_{6}$},
author = {Shreya Das and Anita Halder and Atasi Chakraborty and Indra Dasgupta and Tanusri Saha-Dasgupta},
journal= {arXiv preprint arXiv:2005.02582},
year = {2020}
}