Abstract
Abstract
Lattice thermal-transport properties of heavy-fermion YbT2Zn20-based (T = Co, Rh, and Ir) 1-2-20 compounds are calculated with the single-mode relaxation-time approximation and the full solution of the linearized phonon Boltzmann transport equation from first-principles anharmonic phonon calculations. We predict low lattice thermal conductivity κ
L
with a maximum value of ∼24.16
·K at 85.14 K, 137.29
·K at 9.67 K, and 23.55
·K at 67.50 K and ∼12.02, 40.04, and 10.30
·K at room temperature for YbCo2Zn20, YbRh2Zn20, and YbIr2Zn20, respectively. Based on the analysis of the cumulative κ
L
as a function of the phonon mean free path and the frequency-dependent joint density of states at various temperatures, we attribute the low κ
L
to a rattling mode with an average characteristic rattling frequency
that enhanced phonon scattering processes, which reduced the phonon mean free paths, suppressed the phonon lifetime, and enhanced the probability of three-phonon scattering events. The predicted low κ
L
, especially in YbCo2Zn20 and YbIr2Zn20, makes them promising candidate materials for thermoelectric applications and thermal management.