Entropy Change at the Morin Point of a Hematite Crystal

Abstract

Magnetization of a single crystal of α-Fe₂O₃ was measured in a magnetic field up to 80 kOe in the temperature range below the Morin transition point. From the experimental results and Clapeyron-Clausius’ equation, the entropy change at the transition, ΔS, and the pressure dependence of the Morin point, (dT_M⁄dP)_H, were found to be as follows:
ΔS=0.6×10³ erg/deg·gr,
(dT_M⁄dP)_H=17×10⁻⁹ deg/dyne·cm⁻².