Tunable magnetic orders in CePd₂As₂₋ₓPₓ

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We report the successful synthesis of the polycrystalline compounds CePd₂As₂₋ₓPₓ (0 ≤ x ≤ 2) and their physical properties by measuring the transport, magnetic and thermodynamic behaviors as a function of temperature and/or magnetic field. Powder x-ray diffraction (XRD) indicates that CePd₂As₂₋ₓPₓ crystallizes in the ThCr₂Si₂-type tetragonal structure. CePd₂As₂ exhibits a moderate Sommerfeld coefficient of γ ≈ 88 mJ/mol-K², and undergoes an antiferromagnetic (AFM) transition at the Néel temperature Tₙ ≈ 15 K. Upon substituting As with P, the Tₙ is nearly unchanged up to x ≃ 0.6, while a ferromagnetic (FM) transition develops below Tₙ for x ≃ 0.4. The Curie temperature TC increases with increasing x and eventually merges with the AFM transition at x ≃ 0.6. With further increase of x, the system follows typical FM behaviors and its TC monotonically increases and reaches TC ≈ 28 K in CePd₂P₂. Moreover, a metamagnetic transition is observed in the As-rich samples, but vanishes for x ≥ 0.4. Such a tunable magnetic ground state may provide an opportunity to explore the possible quantum critical behavior in CePd₂As₂₋ₓPₓ.