Magnetic Susceptibility of Cu (NO3)2·2.5H2O at Low Temperature

Abstract

The magnetic susceptibility of cupric nitrate "trihydrate" Cu${\left(\mathrm{N}{\mathrm{O}}_3\right)}_2$·2.5${\mathrm{H}}_2$O has been measured on the powder and on single crystals in the 14-20 and 0.4-4.2°K ranges of temperature. The susceptibility of the powder has a rounded maximum at 3.2°K, where it is equal to 0.065 cgs/mole, and drops very rapidly towards zero below this temperature. This behavior differs from that of a typical antiferromagnet. The experimental data have been compared with existing theoretical calculations for antiferromagnetic linear chains or binary clusters. In the single crystal, the susceptibility measured in a direction parallel to the monoclinic axis is always larger by 20% than the susceptibility in the perpendicular directions. This is probably due to a uniaxial anisotropy of the $g$ factor.