ScholarWorks@성균관대학교

초록

We investigate magnetic properties of the s = 1/2 compound K2Cu3(MoO4)(4) by combining magnetic susceptibility, magnetization, specific heat, and electron spin resonance (ESR) with density functional calculations. Its monoclinic structure features alternating Cu2+ (s = 1/2) monomers and edge-shared dimers linked by MoO4 units, forming a distorted diamond chain along the a axis. Antiferromagnetic order occurs at T-N = 2.3 K, as evident from a lambda-type anomaly in specific heat and magnetic susceptibility derivatives. Inverse magnetic susceptibility reveals coexisting ferro-and antiferromagnetic interactions. Specific heat and ESR data show two characteristic temperatures: one at 20 K, associated with spin-singlet formation in Cu2O9 dimers, and another at 3.68 K, indicating short-range correlations between dimers and monomers. Magnetization measurements reveal a metamagnetic transition at 2.6 T and a critical magnetic field mu H-0(c) = 3.4 T, where a 1/3 magnetization plateau emerges with saturation near 0.35 mu (B). Low-temperature specific heat and magnetization data reveal the suppression of long-range order at mu H-0(c), enabling the construction of a temperature-magnetic field phase diagram showing multiple magnetic phases near the mu H-0(c). Density functional theory confirms a distorted diamond chain with J J1 dimers and competing J(2), J(4), J(3), and J(5) interactions with monomer spins as an effective low-temperature spin model.

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