Theory of magnetic order in Fe1+yTe1-xSexChen Fang1, B. Andrei Bernevig2 and Jiangping Hu1
1 Department of Physics, Purdue University - West Lafayette, IN 47907, USA
2 Princeton Center for Theoretical Science, Princeton University - Princeton, NJ 08544, USA
received 26 January 2009; accepted in final form 25 May 2009; published June 2009
published online 9 July 2009
We develop a local spin model to explain the rich magnetic structures in the iron-based superconductors Fe1+yTe1-xSex. We show that our model exhibits both commensurate antiferromagnetic and incommensurate magnetic order along the crystal a-axis. The transition from the commensurate to the incommensurate phase is induced when the concentration of excess Fe atoms is larger than a critical value. Experimentally measurable spin-wave features are calculated, and the mean-field phase diagram of the model is obtained. Our model also suggests the existence of a large quantum critical region due to strong spin frustration upon increasing Se concentration.
74.25.Ha - Magnetic properties.
71.10.-w - Theories and models of many-electron systems.
71.27.+a - Strongly correlated electron systems; heavy fermions.
© EPLA 2009