用~（153）Eu NMR研究EuFe2As2中的磁退孪晶和双二次磁相互作用
Magnetic detwinning and biquadratic magnetic interaction in EuFe2As2 revealed by 153Eu NMR
摘要：
在铁基超导体的超导态中，孪晶的形成常常使其本征的、各向异性的、面内的物理性质变得模糊不清，通常需要比典型的实验室规模的磁场10- 15 T更大的相对高的面内外磁场$H_{\rm ext}$才能使样品完全去孪晶。然而，最近发现非常小的面内$H_{\rm ext} \sim$ 0.1 T足以使EuFe $_2$ As $_2$中的双晶畴去孪晶。为了解释这种行为，一个微观理论的基础上的Eu和Fe自旋之间的双二次磁相互作用已被提出。在这里，使用$^{153}$ Eu核磁共振（NMR）测量低于Eu $^{2+}$有序温度，我们显示了小的面内$H_{\rm ext}$下的解孪晶的实验证据。我们的NMR研究还揭示了Eu和Fe自旋之间的角度的演变过程中的退孪晶，这提供了第一个实验证据的存在，在系统中的双二次耦合。
英文摘要：
In the nematic state of iron-based superconductors, twin formation often obscures the intrinsic, anisotropic, in-plane physical properties.Relatively high in-plane external magnetic fields $H_{\rm ext}$ greater than the typical lab-scale magnetic fields 10--15 T are usually required to completely detwin a sample. However, recently a very small in-plane $H_{\rm ext} \sim$ 0.1 T was found to be sufficient for detwinning the nematic domains in EuFe$_2$As$_2$. To explain this behavior, a microscopic theory based on biquadratic magnetic interactions between the Eu and Fe spins has been proposed. Here, using $^{153}$Eu nuclear magnetic resonance (NMR) measurements below the Eu$^{2+}$ ordering temperature, we show experimental evidence of the detwinning under small in-plane $H_{\rm ext}$. Our NMR study also reveals the evolution of the angles between the Eu and Fe spins during the detwinning process, which provides the first experimental evidence for the existence of biquadratic coupling in the system.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
