@article{3810fb6cd40b4425b09b72678ba94219,
title = "Low energy spin waves and magnetic interactions in SrFe2As2",
abstract = "We report inelastic neutron scattering studies of magnetic excitations in antiferromagnetically ordered SrFe2As2 (TN=200-220K), the parent compound of the FeAs-based superconductors. At low temperatures (T=7K), the magnetic spectrum S(Q, □ ω) consists of a Bragg peak at the elastic position (□ ω=0meV), a spin gap (Δ≤6.5meV), and sharp spin-wave excitations at higher energies. Based on the observed dispersion relation, we estimate the effective magnetic exchange coupling using a Heisenberg model. On warming across TN, the low-temperature spin gap rapidly closes, with weak critical scattering and spin-spin correlations in the paramagnetic state. The antiferromagnetic order in SrFe2As2 is therefore consistent with a first order phase transition, similar to the structural lattice distortion.",
author = "Jun Zhao and Yao, {Dao Xin} and Shiliang Li and Tao Hong and Y. Chen and S. Chang and W. Ratcliff and Lynn, {J. W.} and Mook, {H. A.} and Chen, {G. F.} and Luo, {J. L.} and Wang, {N. L.} and Carlson, {E. W.} and Jiangping Hu and Pengcheng Dai",
year = "2008",
month = oct,
day = "14",
doi = "10.1103/PhysRevLett.101.167203",
language = "English",
volume = "101",
journal = "Physical Review Letters",
issn = "0031-9007",
publisher = "American Physical Society",
number = "16",
}