Dürrmann Andreas, Hörner Gerald, Baabe Dirk, Heinemann Frank W, de Melo Mauricio A C, Weber Birgit
Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, Jena, Germany.
Inorganic Chemistry IV, University of Bayreuth, Universitätsstraße 30, Bayreuth, Germany.
Nat Commun. 2024 Aug 25;15(1):7321. doi: 10.1038/s41467-024-51675-1.
Cooperativity among spin centres has long been the royal road in spin crossover (SCO) research to impose magnetic bistability in terms of thermal hysteresis. In this work we access magnetic multi-inert states of the iron(III) compound {FeL[B(Ph)]} ≡ FeB at low temperature, in addition to thermal bistability. The packing of the low-spin and high-spin forms of crystalline FeB differs only marginally what ultimately leads to structural conservatism. This indicates that the SCO-immanent breathing of the complex cation is almost fully compensated by the anion matrix. The unique cooling rate dependence of the residual low-temperature magnetisation in FeB unveils continuous switching between the trapped high-spin (ON) and the relaxed low-spin state (OFF). The macroscopic ratio of the spin states (ON:OFF) can be adjusted as a simple function of the cooling rate. That is, cooperative spin crossover can be the source of bistable and multi-inert system states in the very same material.
自旋中心之间的协同作用长期以来一直是自旋交叉（SCO）研究中通过热滞现象实现磁双稳性的重要途径。在这项工作中，我们在低温下除了热双稳性之外，还获得了铁（III）化合物{FeL[B(Ph)]}≡FeB的磁性多惰性状态。晶体FeB的低自旋和高自旋形式的堆积仅略有不同，这最终导致了结构保守性。这表明复合阳离子的SCO固有呼吸几乎完全被阴离子基质所补偿。FeB中残余低温磁化强度对冷却速率的独特依赖性揭示了被困高自旋（开）和弛豫低自旋状态（关）之间的连续切换。自旋态的宏观比例（开：关）可以作为冷却速率的简单函数进行调节。也就是说，协同自旋交叉可以成为同一材料中双稳和多惰性系统状态的来源。
