Large low temperature magnetoresistance and magnetic anomalies in Tb₂PdSi₃ and Dy₂PdSi₃

Abstract

The results of heat-capacity (C), magnetic susceptibility (χ), electrical resistivity (ρ) and magnetoresistance (Δρ/ρ) measurements on the compounds, Tb₂PdSi₃ and Dy₂PdSi₃, are reported. The results establish that these compounds undergo long-range magnetic ordering (presumably with a complex magnetic structure) below (T_c=) 23 and 8 K, respectively. The Δρ/ρ is negative in the vicinity of T_c and the magnitude grows as T_c is approached from higher temperatures as in the case of well-known giant magnetoresistance systems (La manganite-based perovskites); this is attributed to the formation of some kind of magnetic polarons. The magnitude of Δρ/ρ at low temperatures is quite large, for instance, about 30% in the presence of 60 kOe field at 5 K in Dy sample.