Field-induced quantum magnetism in the verdazyl-based charge-transfer salt [o-MePy-V-(p-Br)(2)]FeCl4

Article

关键词: COMPLEXES;   

DOI  :  10.1103/PhysRevB.98.224411

来源: SCIE

【 摘 要 】

We successfully synthesized a verdazyl-based charge-transfer salt [o-MePy-V-(p-Br)(2)]FeCl4, which has S-v = 1/2 on the radical o-MePy-V-(p-Br)(2) and S-Fe = 5/2 on the FeCl4 anion. Ab initio molecular orbital calculations indicate the formation of an S-v = 1/2 honeycomb lattice composed of three types of exchange interaction with two types of inequivalent sites. Further, the S-v = 1/2 at one site is sandwiched by S-Fe = 5/2 spins through antiferromagnetic (AF) interactions. The magnetic properties indicate that the dominant AF interactions between the S-v = 1/2 spins form a gapped singlet state, and the remaining S-Fe = 5/2 spins cause an AF order. The magnetization curve exhibits a linear increase up to approximately 7T, and an unconventional 5/6 magnetization plateau appears between 7 and 40 T. We discuss the differences between the effective interactions associated with the magnetic properties of the present compound and (o-MePy-V)FeCl4. We explain the low-field linear magnetization curve through a mean-field approximation of an S-Fe = 5/2 spin model. At higher field regions, the 5/6 magnetization plateau and subsequent nonlinear increase are reproduced by the S-v = 1/2 AF dimer, in which a particular internal field is applied to one of the spin sites. The ESR signals in the low-temperature and low-field regime are explained by conventional two-sublattice AF resonance modes with easy-axis anisotropy. These results demonstrate that exchange interactions between S-v = 1/2 and S-Fe = 5/2 spins in [o-MePy-V-(p-Br)(2)]FeCl4 realize unconventional magnetic properties with low-field classical behavior and field-induced quantum behavior.

【 授权许可】

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