arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1105.2144cond-mat.str-el
收藏

价态涨落$α$ $_4$中各向异性重费米液体的形成

Anisotropic heavy Fermi-liquid formation in the valence fluctuating $α$-YbAlB$_4$

Yosuke Matsumoto, K. Kuga, T. Tomita, Y. Karaki, S. Nakatsuji

摘要:

$α$ -YbAlB $_4$是$β$ -YbAlB $_4$的局部同构多晶型物,其是Yb基重费米子超导体的第一个例子,其在$T_{\rm c}$之上表现出明显的非费米液体行为。有趣的是,$α$-YbAlB $_4$和$β$-YbAlB $_4$都具有强中间价.我们对$α$-YbAlB $_4$ ~的比热、磁化强度和电阻率的单晶研究证实了它的费米液态基态,与在$β$-YbAlB $_4$中观察到的量子临界态相反.这两个系统都表现出Kondo晶格行为的特征温度标度$T^* \sim$ 8 K除了价涨落标度$\sim 200$ K。在$T^*$以下,$_4$是一种重费米液态,其电子比热系数$γ\sim$ 130 mJ/mol K $^2$和大于7的大Wilson比,表明Yb磁矩之间存在铁磁相关性.在电阻率的大的各向异性表明,4 $f$和传导电子之间的杂交是强得多的$ab$平面比沿c轴。强的各向异性杂化和大的Wilson比是理解混合价化合物中不寻常的近藤晶格行为和重费米子形成的关键。

英文摘要:

$α$-YbAlB$_4$ is the locally isostructural polymorph of $β$-YbAlB$_4$, the first example of an Yb-based heavy fermion superconductor which exhibits pronounced non-Fermi-liquid behavior above $T_{\rm c}$. Interestingly, both $α$-YbAlB$_4$ and $β$-YbAlB$_4$ have strongly intermediate valence. Our single crystal study of the specific heat, magnetization and resistivity has confirmed the Fermi liquid ground state of $α$-YbAlB$_4$ ~in contrast with the quantum criticality observed in $β$-YbAlB$_4$. Both systems exhibit Kondo lattice behavior with the characteristic temperature scale $T^* \sim$ 8 K in addition to a valence fluctuation scale $\sim 200$ K. Below $T^*$, $α$-YbAlB$_4$ a heavy Fermi liquid state with an electronic specific heat coefficient $γ\sim$ 130 mJ/mol K$^2$ and a large Wilson ratio more than 7, which indicates ferromagnetic correlation between Yb moments. A large anisotropy in the resistivity suggests that the hybridization between 4$f$ and conduction electrons is much stronger in the $ab$-plane than along the c-axis. The strongly anisotropic hybridization as well as the large Wilson ratio is the key to understand the unusual Kondo lattice behavior and heavy fermion formation in mixed valent compounds.

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。

↑