Promising thermoelectric properties of heavy-fermion semimetal Pr₃Os₄Ge₁₃

Here we report the magnetic, electronic and thermal transport properties of the heavy-fermion semimetal Pr₃Os₄Ge₁₃with a cage-like structure by means of magnetic susceptibility,χ(T), isothermal magnetization,M(B,T), electrical resistivity,ρ(B,T), Hall coefficient,R_H(T), specific heat,C_p(T), thermal conductivity,κ(T) and thermoelectric power,S(T).ρ(T) andR_H(T) show semimetallic features in a manner that mimics a thermal activated behaviour with an activation energy, Δ/k_B= 6.5 K indicating the opening of a small energy gap in the material. At low temperatures, a Sommerfeld coefficient,γ= 128 mJ (mol^-1K^-2) observed indicates a mass enhancement of the quasiparticles at low temperatures which bears witness to a heavy fermion state in Pr₃Os₄Ge₁₃. A Wilson-Sommerfeld ratio,W_Rand the dimensionless ratio,S/γTof 1.01 and 0.62 ± 0.018 observed, respectively, are in good agreement with the Fermi liquid scenario.S(T) andR_H(T) reveal hole dominated transport (p-type material) with a relatively large room temperature value ofS(T) = 32.85 ± 0.98μV K^-1. A room temperature low value ofκ(T) = 1.61 W K^-1 m^-1leads to a thermoelectric figure of merit,ZT= 0.03 ± 0.001 which is comparable to values achieved in several clathrates around the same temperature. Features fromS(T) andρ(T) favour the realization of a higherZTvalue at elevated temperatures.