Structure and physical properties of new layered iron oxychalcogenide BaFe2OSe2

TL;DR

This paper reports the synthesis and characterization of a new layered iron oxychalcogenide BaFe2OSe2, revealing its semiconducting nature and complex magnetic behavior with possible short-range magnetic correlations above room temperature.

Contribution

The study introduces a novel layered BaFe2OSe2 crystal structure and provides detailed insights into its physical and magnetic properties, including potential antiferromagnetic transition and glassy states.

Findings

BaFe2OSe2 is a semiconductor without Curie-Weiss behavior up to 350 K.

Possible antiferromagnetic transition at 240 K.

Presence of glassy magnetic transitions at 115 K and 43 K.

Abstract

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.