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 ∼1 μJ/K. The measured heat capacity data exhibit a λ-like shape at the Néel temperature TN ≈ 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.