论文标题
量子关键$β$ -YBALB $ _4 $和$α$ -ybal $ _ {0.986} $ fe $ _ {0.014} $ b $ _4 $ _4 $ _4 $
Ultrasound Response in Quantum Critical $β$-YbAlB$_4$ and $α$-YbAl$_{0.986}$Fe$_{0.014}$B$_4$
论文作者
论文摘要
我们分析了重型电子金属$β$ -YBALB $ _4 $中量子价关键性的主要起源通过为$β$ -YBALB $ _4 $构建现实的规范模型，我们评估了Yb $ u _ {\ rm fd} \ 6.2 $ eV的4F和5D电子之间的库仑排斥，以实现Yb-Valence Trescition的量子关键点（QCP）。为了揭示YB 5D对量子临界状态的贡献，我们提出了超声测量。我们发现，不仅散装模量的弹性常数软化，而且剪切模量也是由临界4F和5D电荷波动增强的电动四极波动引起的，QCP的低温。这些结果可能与$β$ -YBALB $ _4 $以及$α$ -YBAL $ _ {1-X} $ fe $ _x $ _x $ b $ _4 $的可能相关性。
We analyze the key origin of quantum valence criticality in the heavy electron metal $β$-YbAlB$_4$ evidenced in the sister compound $α$-YbAl$_{0.986}$Fe$_{0.014}$B$_4$. By constructing a realistic canonical model for $β$-YbAlB$_4$, we evaluate Coulomb repulsion between the 4f and 5d electrons at Yb $U_{\rm fd}\approx 6.2$ eV realizing the quantum critical point (QCP) of the Yb-valence transition. To reveal the Yb 5d contribution to the quantum critical state, we propose ultrasound measurement. We find that softening of elastic constants of not only the bulk modulus but also the shear moduli is caused by electric quadrupole fluctuations enhanced by critical 4f and 5d charge fluctuations for low temperatures at the valence QCP. Possible relevance of these results to $β$-YbAlB$_4$ and also $α$-YbAl$_{1-x}$Fe$_x$B$_4$ is discussed.
