论文标题
在EUFE2AS2中强烈各向异性抗磁磁耦合，应压力揭示
Strongly anisotropic antiferromagnetic coupling in EuFe2As2 revealed by stress detwinning
论文作者
论文摘要
在所有基于铁的高温超导体的母体化合物中，EUFE2AS2均显示出迄今为止最大的磁体结构耦合，这是由于欧盟和FE时矩之间的相当大的二次相互作用。虽然欧盟防铁磁序与FE结构/抗铁磁域之间的耦合可以使快速磁场detwinning，但这可以防止简单的磁力测量测量值提取欧盟元磁过渡的临界场。在这里，我们通过将X射线磁性圆形二色性光谱与原位可调节的单轴应力和施加的磁场相结合来测量这些临界场。两个调谐旋钮的组合使我们能够将结构域的应力消除与欧盟矩的现场诱导的重新定向分开。有趣的是，我们发现一个自旋翼跃迁，只能是由于欧盟平面之间的各向异性相互作用而产生的。我们认为，这种各向异性交换是磁有序的FE层中强各向异性的结果，该层在欧盟和Fe磁性之间提出了一种新形式的高阶耦合形式。
Of all parent compounds of iron-based high-temperature superconductors, EuFe2As2 exhibits by far the largest magnetostructural coupling due to the sizable biquadratic interaction between Eu and Fe moments. While the coupling between Eu antiferromagnetic order and Fe structural/antiferromagnetic domains enables rapid field detwinning, this prevents simple magnetometry measurements from extracting the critical fields of the Eu metamagnetic transition. Here we measure these critical fields by combining x-ray magnetic circular dichroism spectroscopy with in-situ tunable uniaxial stress and applied magnetic field. The combination of two tuning knobs allows us to separate the stress-detwinning of structural domains from the field-induced reorientation of Eu moments. Intriguingly, we find a spin-flip transition which can only result from a strongly anisotropic interaction between Eu planes. We argue that this anisotropic exchange is a consequence of the strong anisotropy in the magnetically ordered Fe layer, which presents a new form of higher-order coupling between Eu and Fe magnetism.
