Strongly anisotropic antiferromagnetic coupling in EuFe2As2 revealed by stress detwinning
Strongly anisotropic antiferromagnetic coupling in EuFe2As2 revealed by stress detwinning
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DOI：
10.1103/physrevb.104.104413
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发表时间：
2020-12
影响因子：
3.7
通讯作者：
Joshua J. Sanchez;G. Fabbris;Yongseong Choi;Yue Shi;P. Malinowski;Shashi Pandey;Jian Liu;I. Mazin;Jong-Woo Kim;P. Ryan;J. Chu
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文献类型：
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作者：
Joshua J. Sanchez;G. Fabbris;Yongseong Choi;Yue Shi;P. Malinowski;Shashi Pandey;Jian Liu;I. Mazin;Jong-Woo Kim;P. Ryan;J. Chu
在铁基高温超导体的所有母体化合物中，EuFe 2As 2由于Eu和Fe矩之间的相当大的双二次相互作用而表现出迄今为止最大的磁结构耦合。虽然Eu的反铁磁秩序和Fe结构/反铁磁域之间的耦合，使快速场解孪晶，这阻止了简单的磁力测量提取的Eu变磁性转变的临界场。在这里，我们测量这些关键领域相结合的x射线磁圆二色光谱与原位可调单轴应力和外加磁场。两个调谐旋钮的组合，使我们能够分离的应力解孪晶的结构域的场诱导的Eu矩的重新取向。有趣的是，我们发现一个自旋翻转转变，这只能导致从一个强烈的各向异性之间的相互作用Eu平面。我们认为，这种各向异性交换的结果是强各向异性的磁有序Fe层，这提出了一种新的形式的高阶耦合之间的Eu和Fe磁性。
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.