Magnetic susceptibility measurement has been carried out on the Haldane system (CH3)4NNi(NO2)3 containing non-magnetic Zn2+ and magnetic Cu2+ impurity ions. For each impure system, magnetic susceptibility is described by the sum of two contributions; one is from the Haldane state and the other is a paramagnetic contribution. The latter contribution increases proportionally with impurity concentration. For 1D system shortened by Zn2+ impurity ions, the paramagnetic contribution obeys the Curie law, and its absolute value of the susceptibility is found to amount nearly 40% of the theoretical estimation for the VBS model where the spin with its value S = 1/2 appears at the both edges of 1D segments. In the case for the system with Cu2+ impurity ions, the paramagnetic contribution is much smaller than the results for the Zn2+ impure systems. This reduction of the magnetic moment of Cu2+ ion for 5 = 1/2 is qualitatively different from the case for the enhanced moment of Cu2+ ion in the anisotropic S = 1 Heisenberg antiferromagnet NENP.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)