Ferromagnetic exchange coupling in sodium biscarbonatocuprate(II) trihydrate

Abstract

The magnetic properties of sodium biscarbonatocuprate(II) trihydrate, Na₂Cu(CO₂)₂,3H₂O, have been measured in the temperature range 1.8-42 K. Magnetic susceptibility and magnetization measurements provide evidence for ferromagnetic interactions in this linear-chain compound. The magnetic susceptibility data are compatible with a Heisenberg linear chain; the best-fit parameters for the complete data set are: J 1.22 ±0.04cm^-1, g 2.18 ± 0.01, and zJ'-0.28 ± 0.02cm^-l. Data in the temperature range 7-42K yield the best-fit parameters J1.37 ± 0.08 cm^-1, g 2.12 ± 0.01, and zJ' 0.0 cm^-1. The g value from this fit agrees with the g value of 2.10 obtained from a fit of the data in the temperature range 10-42 K to the Curie-Weiss law.