Magnetization process of an<i>S=1</i>linear-chain Heisenberg antiferromagnet

Abstract

Magnetization measurements in strong pulsed magnetic fields on single-crystal samples of the S=1 linear-chain Heisenberg antiferromagnet Ni(${\mathrm{C}}_{2}$${\mathrm{H}}_{8}$${\mathrm{H}}_{2}$${)}_{2}$${\mathrm{NO}}_{2}$(${\mathrm{ClO}}_{4}$) are reported. The magnetization is very small at the low-field region and begins to increase sharply at a finite field for all of the three principal axes. This is evidence for the existence of the Haldane gap in this compound.