Bond AlternatingS=1Spin Chain with Single-Ion Anisotropy – Susceptibilities of the Compounds, {Ni₂(EDTA)(H₂O)₄}_n·(2H₂O)_nand [{Ni₂(Medpt)₂(µ-ox)(µ-N₃)}_n](ClO₄)_n

Abstract

One-dimensional S =1 spin systems with bond alternation ( J 1 and J 2 ) and single-ion anisotropy ( D z ) are studied. We numerically diagonalize the Hamiltonians of finite size up to ten spins and calculate the temperature dependence of the susceptibility. The theoretical curves are applied to analyze the susceptibilities of {Ni 2 (EDTA)(H 2 O) 4 } n ·(2H 2 O) n (EDTA= ethylenediaminetetraacetic acid) and [{Ni 2 (Medpt) 2 (µ-ox)(µ-N 3 )} n ](ClO 4 ) n (Medpt=methyl-bis(3-aminopropyl)amine). The estimated results of J 2 / J 1 =0.26, D z / J 1 =0.17, ( J 1 ∼13 K) for {Ni 2 (EDTA)(H 2 O) 4 } n ·(2H 2 O) n and J 2 / J 1 =0.30, D z / J 1 =0.07, ( J 1 ∼43 K) for [{Ni 2 (Medpt) 2 (µ-ox)(µ-N 3 )} n ](ClO 4 ) n are presented. We find that both are systems with the singlet-dimer ground state.