Quasi-one-dimensionalS=12Heisenberg antiferromagnetic chain consisting of the organic radicalp-Br-V

Abstract

We have succeeded in synthesizing single crystals of an organic radical $p$-Br-V [3-(4-bromophenyl)-1,5-diphenylverdazyl]. The dominant intermolecular interactions forming a one-dimensional spin chain are deduced from the molecular packing in the crystal, and the ab initio molecular orbital calculation also indicates such an exchange network. We analyzed the magnetic susceptibility, magnetization curve, and magnetic specific heat through the quantum Monte Carlo method and successfully explained them as being attributed to an $S=\frac{1}{2}$ Heisenberg antiferromagnetic chain. Furthermore, we have found an unexpected successive phase transition in the specific heats, which indicates the formation of a noncollinear magnetic structure induced by frustration.