Antiferroquadrupolar ordering and anisotropic magnetic phase diagram of dysprosium palladium bronze, DyPd₃S₄

From the measurements of magnetization and specific heat, we constructed B-T phase diagrams of single-crystalline DyPd₃S₄ which is known to exhibit antiferroquadrupolar (AFQ) and antiferromagnetic (AFM) ordering at low temperatures. The phase diagrams are found to be highly anisotropic and reentrant, which are typical of rare-earth compounds exhibiting multipolar ordering. The crystalline electric field (CEF) scheme of Dy³⁺ in DyPd₃S₄ was deduced from the specific heat and magnetization measurements of the Y-diluted compounds Dy_1-xY _xPd₃S₄ (0.1 ≤ x ≤ 0.9) and discussed in detail. The CEF ground state was determined to be the orbitally-degenerated quartet Γ₆₇⁽¹⁾, and the overall splitting width was estimated to be about 104 K. No correlation was found between the anisotropy of T_Q and that of the Zeeman splitting width of the ground quartet Γ₆₇⁽¹⁾.