The semiconductor Sr2FeOsO6, depending on temperature, adopts two types of spin structures that differ in the spin sequence of ferrimagnetic iron - osmium layers along the tetragonal c-axis. Neutron powder diffraction experiments, 57Fe M\"ossbauer spectra, and density-functional theory calculations suggest that this behavior arises because a lattice instability resulting in alternating iron-osmium distances fine-tunes the balance of competing exchange interactions. Thus, Sr2FeOsO6 is an example for a double perovskite, in which the electronic phases are controlled by the interplay of spin, orbital, and lattice degrees of freedom.
@article{arxiv.1307.2587,
title = {Lattice Instability and Competing Spin Structures in the Double Perovskite Insulator Sr2FeOsO6},
author = {Avijit Kumar Paul and Manfred Reehuis and Vadim Ksenofontov and Binghai Yan and Andreas Hoser and Daniel M. Többens and Peter Adler and Martin Jansena and Claudia Felser},
journal= {arXiv preprint arXiv:1307.2587},
year = {2013}
}