Multistage development of short-range spin correlations and weak magnetic order in the two coupled trillium lattices of K2Fe2(MoO4)(PO4)2

초록

Trillium lattices, where magnetic ions form a chiral network of corner-sharing triangles, offer a threedimensional magnetic framework that can host fragile classical spin-liquid states. Herein, we report on the magnetization, specific heat, electron spin resonance (ESR), and muon spin relaxation (& micro;SR) of K2Fe2(MoO4)(PO4)2 single crystals. Magnetization measurements reveal strong antiferromagnetic interactions coexisting with weak magnetic order at TN = 5.2 K, as evidenced by a )-like anomaly observed in the magnetic susceptibility, a critical enhancement of the muon spin relaxation rate and the wipeout of the ESR signal as the temperature approaches TN. Above TN, two distinct developments of short-range spin correlations are identified at TH = 34 K and TL = 10 K, supported by magnetic specific heat anomalies and the temperature dependence of the ESR linewidth and g factor. Upon cooling below TN, an anomaly appears at T & lowast; = 3.2 K in thermodynamic observables and the muon spin relaxation rate, indicative of spin reorientation driven by residual interactions. Despite the presence of magnetic order, & micro;SR experiments reveal dynamically fluctuating spins persisting even in the ordered state. Moreover, the suppression of TN under applied magnetic fields (& micro;0H 2 T) suggests that K2Fe2(MoO4)(PO4)2 constitutes a promising candidate for exploring field-induced spin-liquid behavior in three-dimensionally coupled trillium lattices.

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