The Latent Heat of the Spin-Flip Transition in Chromium

The spin density waves of antiferromagnetic chromium are characterized by a transversal polarization of the spins between the Neel point and the spin-flip temperature Tsf while for temperatures below Tsf the spins are longitudinally polarized. The transition at Tsf is of first order. We report here direct measurements of the latent heat of this transition on a vapour-grown chromium crystal using a differential calorimetric technique. The latent heat determined is 0.04 ± 0.02 J/g-atom and Tsf is 123.2 ± 0.4 K. A thermal hysteresis of 0.8 deg. was observed at the transition. The magnitude of the latent heat correlates well with the pressure dependence of Tsf through the Clausis-Clapeyron relationship.