Specific heat of a YCrO3 single crystal as investigated by a Si-N membrane based microcalorimeter

We report the specific heat measurement of a YCrO3 single crystal in a wide temperature range from 30 to 360 K by use of a newly designed microcalorimeter with high sensitivity about similar to 1 mu J/K. The measured heat capacity data exhibit a lambda-like shape at the Neel temperature T-N approximate to 140 K as consistent with the second order magnetic transition. When the phonon specific heat is subtracted by use of that of a non-magnetic analogue LaGaO3 with an orthorhombic structure, the remaining entropy is much higher than the expected magnetic entropy from Cr3+ (S = 3/2) ions. We attribute the excess entropy to the additional phonon entropy caused by the monoclinic structure of YCrO3, which can be intimately related to its ferroelectric property. (C) 2006 Elsevier B.V. All rights reserved.