Iron-Based Heavy Quasiparticles in SrFe$_{4}$Sb$_{12}$: An Infrared Spectroscopic Study

TL;DR

This study uses infrared spectroscopy to reveal heavy quasiparticles in SrFe$_{4}$Sb$_{12}$, showing temperature-dependent mass enhancement and pseudogap formation linked to Fe 3d spin hybridization.

Contribution

It provides direct spectroscopic evidence of iron-based heavy quasiparticles and their temperature-dependent behavior in SrFe$_{4}$Sb$_{12}$.

Findings

Development of a heavy effective mass at low temperatures.

Observation of a 10 meV pseudogap in optical spectra.

Strong temperature dependence of effective mass and scattering rate.

Abstract

Temperature-dependent infrared reflectivity spectra of SrFe$_{4}$Sb$_{12}$ has been measured. A renormalized Drude peak with a heavy effective mass and a pronounced pseudogap of 10 meV develops in the optical conductivity spectra at low temperatures. As the temperature decreases below 100 K, the effective mass ($m^{*}$) rapidly increases, and the scattering rate ($1/\tau$) is quenched. The temperature dependence of $m^{*}$ and $1/\tau$ indicates that the hybridization between the Fe 3d spins and the charge carriers plays an important role in determining the physical properties of SrFe$_{4}$Sb$_{12}$ at low temperatures. This result is the clear evidence of the iron-based heavy quasiparticles.