Specific Heat and Magnetic Susceptibility Studies on Bromobis (1,4‐Diazacycloheptane) Copper(II) Perchlorate, [Cu(dach)₂Br](C10₄), at Low Temperatures

Specific heat and magnetization investigations are made on polycrystalline [Cu(dach)₂Br](Cl0₄) at low temperatures. For temperatures above 25 K, the dc magnetization shows a Curie‐Weiss behaviour with a Curie constant of 7.92 × 10³ e.m.u. K/g and a paramagnetic Curie temperature of −60.8 K. The downturn of 1/X vs. T below 25 K is indicative of ferrimagnetic system. The specific heat between 4 and 8 K can be described by the relation: C = 11.9T³ mJ/mol K with the cubic term leading to a Debye temperature of θ_D = 194 K. Below 4 K the specific heat rises very rapidly suggesting magnetic ordering. This is substantiated by the presence of a sharp peak at 0.95 K in the ac susceptibility results which can be interpreted as being due to a ferrimagnetic phase transition. Both the magnetization and specific heat investigations indicate the behavior of the system to be ferromagnetic at low temperatures which is interpreted as the result of the canted antiferromagnetism of sublattice moments.