Zhang Qiang, Fernandes Rafael M, Lamsal Jagat, Yan Jiaqiang, Chi Songxue, Tucker Gregory S, Pratt Daniel K, Lynn Jeffrey W, McCallum R W, Canfield Paul C, Lograsso Thomas A, Goldman Alan I, Vaknin David, McQueeney Robert J
Ames Laboratory, Ames, Iowa 50011, USA and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Phys Rev Lett. 2015 Feb 6;114(5):057001. doi: 10.1103/PhysRevLett.114.057001. Epub 2015 Feb 4.
Inelastic neutron scattering is employed to investigate the impact of electronic nematic order on the magnetic spectra of LaFeAsO and Ba(Fe(0.953)Co(0.047))(2)As(2). These materials are ideal to study the paramagnetic-nematic state, since the nematic order, signaled by the tetragonal-to-orthorhombic transition at T(S), sets in well above the stripe antiferromagnetic ordering at T(N). We find that the temperature-dependent dynamic susceptibility displays an anomaly at T(S) followed by a sharp enhancement in the spin-spin correlation length, revealing a strong feedback effect of nematic order on the low-energy magnetic spectrum. Our findings can be consistently described by a model that attributes the structural or nematic transition to magnetic fluctuations, and unveils the key role played by nematic order in promoting the long-range stripe antiferromagnetic order in iron pnictides.
非弹性中子散射被用于研究电子向列序对LaFeAsO和Ba(Fe(0.953)Co(0.047))(2)As(2)磁谱的影响。这些材料是研究顺磁向列态的理想材料，因为由T(S)处的四方到正交转变所标志的向列序，在远高于T(N)处的条纹反铁磁序时出现。我们发现，与温度相关的动态磁化率在T(S)处呈现异常，随后自旋-自旋关联长度急剧增加，揭示了向列序对低能磁谱的强烈反馈效应。我们的发现可以通过一个将结构或向列转变归因于磁涨落的模型得到一致描述，该模型揭示了向列序在促进铁基磷化物中长程条纹反铁磁序方面所起的关键作用。
