The magnetization curves, as well as electron spin resonance and nuclear magnetic resonance spectra of ⁸⁷Rb⁺ ions, have been measured in the quasi-two-dimensional antiferromagnet RbFe(MoO₄)₂ on a triangular lattice with the random modulation of the exchange bond network. Random modulation has been performed by means of the partial substitution of nonmagnetic Rb⁺ ions for K⁺ ions. It has been shown that random static disorder thus created at an impurity ion concentration of 15% drastically changes the spin structure. A noncollinear structure with significant sublattice magnetization components transverse to the magnetic field occurs in the doped compound. At the same time, the spin structure in the pure compound has the same magnetic moment, but transverse spin components disappear near a magnetic field of one third of the saturation field (three-sublattice structure with two upward sublattices and one downward sublattice). The revealed doping-induced drastic rearrangement of the spin structure of the triangular antiferromagnet has been explained by the interplay between the contribution of dynamic fluctuations, which makes maximally collinear states favorable in free energy, and the contribution from freeze-in disorder, which ensures the energy gain for the maximally noncollinear arrangement of sublattices.

中文翻译：

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带有非磁性离子的“三角反铁磁体” RbFe（MoO 4）2

在准二维反铁磁体RbFe（MoO ₄）₂的三角形晶格上，通过交换键的随机调制，测量了⁸⁷ Rb ⁺离子的磁化曲线以及电子自旋共振和核磁共振光谱。网络。通过将非磁性Rb ⁺离子部分替换为K ⁺来执行随机调制离子。已经表明，由此在15％的杂质离子浓度下产生的随机静电无序极大地改变了自旋结构。在掺杂的化合物中会出现非共线结构，该结构具有与磁场垂直的明显的子晶格磁化分量。同时，纯化合物中的自旋结构具有相同的磁矩，但是横向自旋分量在饱和场的三分之一的磁场附近消失（三个亚晶格结构，具有两个向上的子晶格和一个向下的子晶格）。揭示了掺杂引起的三角反铁磁体自旋结构的剧烈重排是通过动态波动的影响之间的相互作用来解释的，这使得最大共线态对自由能有利，