Department of Physics, University of California Davis, Davis, California 95616 USA.
Phys Rev Lett. 2019 Feb 8;122(5):057201. doi: 10.1103/PhysRevLett.122.057201.
Applying linear response and the magnetic force theorem in correlated density functional theory, the intersublattice exchange constants of antiferromagnetic Eu are calculated and found to vanish near the pressure of P_{c}=82 GPa, just where magnetic order is observed experimentally to be lost. The Eu 4f^{7} moment remains unchanged at high pressure, again in agreement with spectroscopic measurements, leaving the picture of perfect frustration of interatomic Ruderman-Kittel-Kasuya-Yoshida couplings in a broad metallic background, leaving a state of electrons strongly exchange coupled to arbitrarily oriented, possibly quasistatic local moments. This strongly frustrated state gives way to superconductivity at T_{c}=1.7 K, observed experimentally. These phenomena, and free energy considerations related to correlations, suggest an unusual phase of matter that is discussed within the scenarios of the Doniach Kondo lattice phase diagram, the metallic spin glass class, and itinerant spin liquid or spin gas systems.
应用线性响应和关联密度泛函理论中的磁力定理，计算了反铁磁 Eu 的亚晶格间交换常数，发现其在压力 P_{c}=82 GPa 附近趋于零，而实验中观察到的磁有序正是在此压力下消失。在高压下，Eu 4f^{7}磁矩保持不变，这与光谱测量结果一致，从而形成了在宽金属背景下原子间 Ruderman-Kittel-Kasuya-Yoshida 耦合完全受挫的图像，留下了电子与任意取向、可能是准静态局域磁矩强烈交换耦合的状态。这种强烈受挫的状态在 T_{c}=1.7 K 时转变为超导，这在实验中得到了观察。这些现象以及与相关性相关的自由能考虑表明，存在一种不寻常的物质相，该相在 Doniach Kondo 晶格相图、金属自旋玻璃类和巡游自旋液体或自旋气体系统的情景中进行了讨论。
