论文标题
欧盟$^{2+} $ spins in rbeu（fe $ _ {1-x} $ ni $ _ {x} $）$ _ {4} $的进化
Evolution from helical to collinear ferromagnetic order of the Eu$^{2+}$ spins in RbEu(Fe$_{1-x}$Ni$_{x}$)$_{4}$As$_{4}$
论文作者
论文摘要
EU $^{2+} $在最近发现的RBEU（Fe $ _ {1-X} $ ni $ _ {x} $）$ _ {4} $ as $ _ {4} $ _ {4} $超导体研究中，Neutmon Powdraction Powdraction firfaction Mesuroments研究了Eu $^{2+} $旋转的地面磁性结构。发现随着超导性的抑制，Ni掺杂的增加，欧盟sublattice的磁传播载体会减小，对应于相邻欧盟层中矩之间的旋转角度下降。在$ \ mathit {c} $轴上对铁磁欧盟层进行了螺旋调节，并在两个Ferromagnetic Superconductor RBEU（Fe $ _ {0.95} $ ni $ _ $ _ {0.05} $ _ {0.05} $ _ {4} $ _ {4} $ __ {4} $ _____________________________________________________________________ {0.95} $ ni $ _ {0.05} $ _ {0.05} $ _ {4} $ _ {4} $中Ferromagnet rbeu（fe $ _ {0.93} $ ni $ _ {0.07} $）$ _ {4} $ as $ _ {4} $。这样的螺旋结构转变为非共线铁磁性结构，用于非perconductucting rbeu（fe $ _ {0.91} $ ni $ _ {0.09} $）$ _ {4} $ as $ _ {4} $，带有EU $ $^{2+} $ spin eu eu $ _ {4} $，沿着TETER（1 1）。欧盟$^{2+} $旋转Ni掺杂的旋转的螺旋形成到共线铁磁序的演变得到了第一原理计算的支持。可以通过考虑由间接Ruderman-Kittel-Kasuya-Yosida（Rkky）相互作用的磁交换耦合的变化来很好地解释相邻EU $^{2+} $层之间旋转角的变化。
The ground-state magnetic structures of the Eu$^{2+}$ spins in recently discovered RbEu(Fe$_{1-x}$Ni$_{x}$)$_{4}$As$_{4}$ superconductors have been investigated by neutron powder diffraction measurements. It is found that as the superconductivity gets suppressed with the increase of Ni doping, the magnetic propagation vector of the Eu sublattice diminishes, corresponding to the decrease of the rotation angle between the moments in neighboring Eu layers. The ferromagnetic Eu layers are helically modulated along the $\mathit{c}$ axis with an incommensurate magnetic propagation vector in both the ferromagnetic superconductor RbEu(Fe$_{0.95}$Ni$_{0.05}$)$_{4}$As$_{4}$ and the superconducting ferromagnet RbEu(Fe$_{0.93}$Ni$_{0.07}$)$_{4}$As$_{4}$. Such a helical structure transforms into a purely collinear ferromagnetic structure for non-superconducting RbEu(Fe$_{0.91}$Ni$_{0.09}$)$_{4}$As$_{4}$, with all the Eu$^{2+}$ spins lying along the tetragonal (1 1 0) direction. The evolution from helical to collinear ferromagnetic order of the Eu$^{2+}$ spins with increasing Ni doping is supported by first-principles calculations. The variation of the rotation angle between adjacent Eu$^{2+}$ layers can be well explained by considering the change of magnetic exchange couplings mediated by the indirect Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction.
