We have successfully synthesized a new layered iron oxychalcogenide BaFe2OSe2 single crystal. This compound is built up of Ba and Fe-Se(O) layers alternatively stacked along the c-axis. The Fe-Se(O) layers contain double chains of edge-shared Fe-Se(O) tetrahedra that propagate along the b-axis and are bridged by oxygen along the a-axis. Physical property measurements indicate that BaFe2OSe2 is a semiconductor without the Curie-Weiss behavior up to 350 K. There is a possible long range antiferromagnetic (AFM) transition at 240 K, corresponding to the peak in specific heat measurement and two glassy transitions at 115 K and 43 K. The magnetic entropy up to 300 K is much smaller than the expected value for Fe2+ in tetrahedral crystal fields and Mosbauer spectrum indicates that long range magnetic order is unlikely at 294 K. Both results suggest that a short range magnetic correlations exist above the room temperature.
@article{arxiv.1206.5788,
title = {Structure and physical properties of new layered iron oxychalcogenide BaFe2OSe2},
author = {Hechang Lei and Hyejin Ryu and John Warren and A. I. Frenkel and V. Ivanovski and B. Cekic and C. Petrovic},
journal= {arXiv preprint arXiv:1206.5788},
year = {2015}
}