Heat-capacity studies in the Y_5-xDy_xOs₄Ge₁₀ system

Abstract

In this paper, we confirm the coexistence of superconductivity and antiferromagnetism in the Y_5-xDy_xOs₄Ge₁₀ system which forms in the tetragonal structure leading to space group P/4mbm. In an earlier study, we have reported a possible coexistence of superconductivity and antiferromagnetism from magnetic susceptibility (χ), resistivity, and magnetoresistance measurements in the same system. Here, we report heat-capacity (C_p) and magnetization data for the same system which establish not only the bulk nature of antiferromagnetic ordering in Dy₅Os₄Ge₁₀ but also the coexistence of bulk superconductivity and antiferromagnetism in Y₂Dy₃Os₄Ge₁₀. Preliminary magnetization measurements have been made on the superconductor Y₅Os₄Ge₁₀ to estimate its lower and upper critical fields at T=0 K. Our heat-capacity data on Dy samples show considerable contribution from Schottky effect due to the crystal fields and we have proposed a model (which incorporates Ruderman-Kittel-Kasuya-Yosida exchange interaction) which fits well to the temperature dependence of χ and C_p of all Dy samples with the same crystal-field parameters.