We report on a spin-polarized inelastic neutron scattering study of spin waves in the antiferromagnetically ordered state of BaFe2As2. Three distinct excitation components are identified, with spins fluctuating along the c-axis, perpendicular to the ordering direction in the ab-plane, and parallel to the ordering direction. While the first two "transverse" components can be described by a linear spin-wave theory with magnetic anisotropy and inter-layer coupling, the third "longitudinal" component is generically incompatible with the local moment picture. It points towards a contribution of itinerant electrons to the magnetism already in the parent compound of this family of Fe-based superconductors.
Measurement of Coherent Polarons in the Strongly Coupled Antiferromagnetically Ordered Iron-Chalcogenide Fe1.02Te using Angle-Resolved Photoemission Spectroscopy
Shubnikov-de Haas effect and Yamaji oscillations in the antiferromagnetically ordered organic superconductor k-(BETS)2FeBr4: A Fermiology study
在有机超导体$κ$ -（BETS）$_2$ FeBr $_4$中观察到了Shubnikov-De Haas效应（SdH）和角相关磁电阻振荡（AMRO）。与其同构化合物$κ-(BETS)$ _2 $FeCl$ _4 $, SdH oscillations, for fields perpendicular to the conducting planes, reveal three Fermi Surface (FS) closed orbits $ α $, $ β $, and $ γ $ whose cross sectional areas are 19.8 %, 99.9 %, and 2.4 % of the first Brillouin zone, respectively. The conduction electron effective masses were found to be: $ μ_α =（4.7 \pm 0.2）$ m$ _e $, $ μ_β =（8.0 \pm 1.0）$ m$ _e $, and $ μ_γ =（2.0 \pm 0.2）$ m$ _e $. The observation of a $ γ $ orbit is not expected from band structure calculations, $ μ_β $ is …
Evidence for interfacial superconductivity in a bi-collinear antiferromagnetically ordered FeTe monolayer on a topological insulator
铁基化合物中高温超导性的发现[1，2]引发了对超导性和磁性之间相互作用的大量研究[3]，最近，通过界面效应提高转变温度[4]。人们普遍认为，最佳超导性的出现与长程反铁磁（AFM）有序的抑制密切相关，尽管由于缺乏原子空间分辨率的数据，这种关系的精确微观图像仍然难以捉摸[1][5-7]。在这里，我们提出了一个自旋极化扫描隧道光谱（SP-STS）的研究，铁碲$_{1-x}$硒$_x$（x = 0，0.5）薄膜生长在原型Bi基块体拓扑绝缘体。令人惊讶的是，我们发现在费米能级处的能隙表明，与非超导FeTe体化合物相比，生长在Bi 2 Te 3衬底上的一个单胞薄FeTe层的超导相关性高达Tc ~ 6 K [8]。此外，SP-STS揭示了能隙空间共存的双共线原子力显微镜秩序。这一发现为铁基超导体中竞争有序的理论研究以及拓扑绝缘体和超导层异质结构中奇异相的实验研究开辟了新的视角。
Single-crystal growth and dependences on the hole concentration and magnetic field of the magnetic ground state in the edge-sharing CuO$_2$ chain system Ca$_{2+x}$Y$_{2-x}$Cu$_5$O$_{10}$
用$0 \le x \le 1.67$成功地生长了大尺寸的Ca $_{2+x}$ Y $_{2-x}$ Cu $_5$ O $_{10}$单晶，并测量了其磁化率、比热和磁化曲线，研究了共边CuO $_2$链的磁基态随空穴浓度和磁场的变化.在$0 \le x \le 1.3$中，已经发现具有沿b轴的磁易轴的反铁磁有序相被稳定，并且通过施加平行于b轴的磁场发生自旋翻转转变。反铁磁转变温度随着$x$的增加而降低，并在$x =$ 1.4附近消失。或者，在$x = 1.5$周围出现自旋玻璃相。在空穴浓度为$\sim$ 1/3/Cu的$x = 1.67$下，由于自旋单重态对的形成，似乎形成了自旋能隙态。在Ca $_{2+x}$ Y $_{2-x}$ Cu $_5$ O $_{10}$中没有发现反铁磁有序态和自旋能隙态共存的迹象。
Spin Waves and Spatially Anisotropic Exchange Interactions in the $\mathrm{S=2}$ Stripe Antiferromagnet Rb$_{0.8}$Fe$_{1.5}$S$_2$
用中子非弹性散射方法研究了绝缘Rb $_{0.8}$ Fe $_{1.5}$ S $_2$在布里渊区的条纹反铁磁序自旋波。自旋波谱很好地描述了海森堡哈密顿与各向异性的面内交换相互作用。对有序矩和自旋涨落进行积分，得到$27.6\pm4.2μ_B^2$ /Fe的总矩平方，与$\mathrm{S \approx 2}$一致。不同于$X$ Fe $_2$ As $_2$（$X=$ Ca，Sr和Ba），其中巡回电子有显着的贡献，我们的数据表明，Rb $_{0.8}$ Fe $_{1.5}$ S $_2$中的这种条纹反铁磁有序相是一个莫特状绝缘体，具有完全本地化的$3d$电子和高自旋基态配置。然而，各向异性交换耦合似乎是普遍的，在条纹相的铁磷属化物和硫属化物。
