Susceptibility and high field magnetization measurements have been performed on powdered samples of $\left[\{\mathrm{Ni}\right(333-\mathrm{tet}\left)\right(\mu -{\mathrm{N}}_3\left){\}}_n\right]({\mathrm{ClO}}_4{)}_n$ [333-tet denotes tetraamine ${N,N}^{\prime }$-bis(3-aminopropyl)-1,3-propanediamine]. As the temperature is decreased, the susceptibility exhibits a smooth maximum around 120 K and decreases gradually down to 10 K, and then decreases rapidly. Magnetization up to 50 T at 1.4 K shows no gap in this compound within the experimental accuracy. We have carried out numerical calculations for the $S=1\mathrm{}$ antiferromagnetic bond alternating chain and obtained very good agreement between experiments and calculations for the alternating ratio $\alpha =0.6\mathrm{}$.

• Received 7 July 1997

DOI:https://doi.org/10.1103/PhysRevLett.80.1312