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

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

doi:10.1103/PhysRevB.84.125126

paper

Anisotropic heavy Fermi-liquid formation in the valence fluctuating $α$ -YbAlB $_{4}$

arXiv:1105.2144 · doi:10.1103/PhysRevB.84.125126

Abstract

$α$ -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 $T_{c}$ . 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.

7 pages, 6 figures

Anisotropic heavy Fermi-liquid formation in the valence fluctuating $α$ -YbAlB $_{4}$

Abstract

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Anisotropic heavy Fermi-liquid formation in the valence fluctuating α-YbAlB4​

Abstract

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Cited by in corpus (21)

Anisotropic heavy Fermi-liquid formation in the valence fluctuating $α$ -YbAlB $_{4}$