Spin-State Crossover Model for the Magnetism of Iron Pnictides
| Authors | |
|---|---|
| Year of publication | 2013 |
| Type | Article in Periodical |
| Magazine / Source | Physical Review Letters |
| MU Faculty or unit | |
| Citation | |
| Web | http://prl.aps.org/abstract/PRL/v110/i20/e207205 |
| Doi | http://dx.doi.org/10.1103/PhysRevLett.110.207205 |
| Field | Solid matter physics and magnetism |
| Keywords | iron pnictides; quantum magnetism; spin-state crossover |
| Description | We propose a minimal model describing magnetic behavior of Fe-based superconductors. The key ingredient of the model is a dynamical mixing of quasidegenerate spin states of Fe2+ ion by intersite electron hoppings, resulting in an effective local spin Seff. The moments Seff tend to form singlet pairs and may condense into a spin nematic phase due to the emergent biquadratic exchange couplings. The longrange ordered part m of Seff varies widely, 0<=m<=Seff, but magnon spectra are universal and scale with Seff, resolving the puzzle of large but fluctuating Fe moments. Unusual temperature dependences of a local moment and spin susceptibility are also explained. |
| Related projects: |