Ferromagnetic cluster spin-glass behavior in PrRhSn ₃

We report the synthesis, structure, and magnetic and transport properties of a new ternary intermetallic compound PrRhSn ₃, which crystallizes in LaRuSn ₃-type cubic structure (space group Pm3̄n). At low applied fields, the dc magnetic susceptibility exhibits a sharp anomaly below 6 K with an irreversible behavior in zero-field-cooled (ZFC) and field-cooled (FC) susceptibility below 5.5 K. The ac susceptibility exhibits a frequency-dependent anomaly, revealing a spin-glass behavior with a freezing temperature T _f = 4.3 K. The observation of spin-glass behavior is further supported by a very slow decay of thermoremnant magnetization (mean relaxation time τ = 2149 s). However, a small jump at very low field in the isothermal magnetization at 2 K and a weak anomaly in the specific heat near 5.5 K reveal the presence of ferromagnetic clusters. The frequency dependence of the transition temperature T _f in the ac susceptibility obeys the Vogel-Fulcher law ν=ν ₀exp[-E _a/k _B(T _f-T ₀)] with activation energy E _a/k _B = 19.1 K. This, together with an intermediate value of the parameter δT _f=ΔT _f/T _fΔ(log ₁₀ν) = 0.086, provides an evidence for the formation of a cluster glass state in PrRhSn ₃. Further, we have analyzed the frequency dependence of transition temperature within the framework of critical slowing down, τ=τ ₀ ^[(T _f ^-T _SG ^)/T _SG ^)-zν ^′], and found the characteristic time constant τ ₀ = 2.04 × 10 ^-10 s and critical exponent zν ^′ = 10.9, which also support a cluster spin-glass behavior in this compound. The magnetic contribution of the specific heat reveals a broad Schottky-type anomaly centered around 10 K, and the analysis based on the crystal-electric-field model indicates a singlet ground state. Further, below T _f, the magnetic part of the specific heat exhibits a T3 ^/2 temperature dependence. The strong influence of the crystal electric field and a T3 ^/2 temperature dependence are also seen in the electrical resistivity, which reveals a metallic character and a high magnetoresistance. We also obtain a surprisingly large value of Sommerfeld-Wilson ratio R _W247.