Fig. 1. CpT -1 vs T curves of chiral and racemic W-Cu complexes. Large thermal anomalies are originated from magnetic phase transitions of W and Cu spins in both samples.
We have performed heat capacity measurements for a chiral molecular magnet [W(CN)8]4[Cu(pn)H2O]4[Cu(pn)]2∙2.5H2O (pn = 1,2-diaminopropane). We observed strong anisotropic behavior when magnetic field was applied in bc plane. When magnetic field was applied parallel to c-axis, a large thermal anomaly originated from magnetic transition was suppressed. This is a typical behavior of antiferromagnetic compounds. On the other hand, when magnetic field was applied parallel to b-axis, very sharp anomaly was induced. We confirmed that this compound exhibits magnetic field induced first order transition under magnetic field parallel to b-axis. The clear magnetic structure of chiral compound is not revealed but we expect that this peculiar thermal behavior is derived from chiral magnetic ordering.
Fig. 1. CpT -1 vs T curves of chiral and racemic W-Cu complexes. Large thermal anomalies are originated from magnetic phase transitions of W and Cu spins in both samples.
Fig. 2. Heat capacities of chiral W-Cu complex under magnetic field parallel to b-axis.
Fig. 3. Heat capacities of chiral W-Cu complex under magnetic field parallel to c-axis.