Terahertz Electrodynamics of Mixed-Valent YbAl${}_3$ and LuAl${}_3$ Thin Films

Abstract

We present THz measurements of thin films of mixed-valent YbAl${}_3$ and its structural analogue LuAl${}_3$. Combined with traditional Fourier transform infrared (FTIR) spectroscopy, the extended Drude formalism is utilized to study the low-frequency transport of these materials. We find that LuAl${}_3$ demonstrates conventional Drude transport whereas at low temperatures YbAl${}_3$ demonstrates a sharply renormalized Drude peak and a mid-infrared (MIR) peak in the conductivity, indicative of the formation of a heavy Fermi liquid. In YbAl${}_3$ the extended Drude framework shows a consistency of the scattering rate with Fermi-liquid behavior below $T<40$ K and a moderate mass enhancement. While a ${\omega }^2$ Fermi liquid-like frequency dependence is not clearly exhibited, the temperature dependence of the Drude scattering rate and effective mass is consistent with the formation of a low-temperature moderately heavy Fermi liquid, albeit one with a smaller mass than observed in single crystals. The extended Drude analysis also supports a slow crossover between the Fermi liquid state and the normal state in YbAl${}_3$.

arXiv comment8 pages, 8 figures

References in corpus (14)

• Kramers-Kronig constrained variational analysis of optical spectra
• Emergence of superconductivity in the canonical heavy-electron metal YbRh2Si2
• Protracted Screening in the Periodic Anderson Model
• Magnetic properties and heat capacity of the three-dimensional frustrated S=1/2 antiferromagnet PbCuTe2O6
• Slow crossover in YbXCu4 intermediate valence compounds
• β-YbAlB4: a critical nodal metal
• Pseudogap Formation and Heavy Carrier Dynamics in Intermediate Valence YbAl3
• How Kondo Holes Create Intense Nanoscale Heavy-Fermion Hybridization Disorder
• Field dependent effective masses in YbAl${}_3$
• Multiple temperature scales of the periodic Anderson model: the slave bosons approach
• From mixed valence to the Kondo lattice regime
• Coherence Temperature in the Diluted Periodic Anderson Model
• Anomalous frequency and temperature dependent scattering and Hund's coupling in the almost quantum critical heavy fermion system CeFe${}_2$Ge${}_2$
• Epitaxial growth and electronic properties of mixed valence YbAl3 thin films