High-Field Magnetism of the Spin-Ladder Material Na2Fe2(C2O4)(3)(H2O)(2)

作者：Yamaguchi Hironori^*; Kimura Shojiro; Honda Zentaro; Okunishi Kouichi; Todo Synge; Kindo Koichi; Hagiwara Masayuki

来源：Journal of the Physical Society of Japan, 2009, 78(12): 124701.

DOI：10.1143/JPSJ.78.124701

• high-field ESR
• high-field magnetization
• spin-ladder
• antiferromagnetic dimer

We report the results of our magnetic susceptibility, magnetization, and multi-frequency electron spin resonance (ESR) measurements on single crystals of the two-leg spin-ladder material Na2Fe2(C2O4)(3)(H2O)(2). Magnetization processes in magnetic fields up 53 T at 1.3 K parallel (H parallel to a) and perpendicular (H perpendicular to a) to the leg direction show a gradual increase compared with those of the isomorphous compound Na2Co2(C2O4)(3)(H2O)(2), which was well explained by an isolated antiferromagnetic dinner model. Thus, we calculated the magnetic susceptibilities and magnetizations on the basis of a two-leg ladder model with a fictitious spin (S) one by a quantum Monte Carlo method and a density-matrix renormalization group method, respectively. These calculated results, however, did not agree well with the experimental ones. Therefore, we regarded Na2Fe2(C2O4)(3)(H2O)(2) as an isolated S = 1 antiferromagnetic dimer with not only the anisotropy of the exchange interactions due to the truncation of spin space but also single-ion anisotropy. Consequently, we obtained good agreement between the experimental and calculated results on the magnetic susceptibilities, magnetizations, ESR resonance modes, and specific heat.

• 出版日期2009-12