Magnetic Properties of S=1/2 Antiferromagnetic Alternating Chain in a New Salt (o-MePy-V)(TCNQ)

摘要

We successfully synthesized the verdazyl-based salt (o-MePy-V)(TCNQ) [o-MePy-V = 3-(2-methylpyridyl)-1,5-diphenylverdazyl; TCNQ = 7,7,8,8-tetracyanoquinodimethane]. Ab initio molecular orbital calculations indicate that the two dominant antiferromagnetic (AF) interactions, J(1) and J(2), form an S= 1/2 Heisenberg AF alternating chain. Magnetic susceptibility of the compound exhibits thermally activated behavior below approximately 30K. Furthermore, the high-field magnetization measurement reveals an excitation energy gap of approximately 40T. We successfully explain those experimental results in terms of the S= 1/2 Heisenberg AF alternating chain with the parameters J(1)/k(B) = 77.8 K and J(2)/K-B = 20.2 K (J(2)/J(1) = 0.26).