The magnetic susceptibility, specific heat and dielectric constant of hexagonal YMnO3, LuMnO3 and ScMnO3

We report the magnetic susceptibility, specific heat and dielectric constant for high-purity polycrystalline samples of three hexagonal manganites: YMnO3, LuMnO3 and ScMnO3. These materials can exhibit a ferroelectric transition at very high temperatures (T-FE > 700 K) At lower temperatures there is magnetic ordering of the frustrated Mn3+ spins (S = 2) on a triangular Mn lattice (YMnO3: T-N = 71 K; LuMnO3: T-N = 90 K and ScMnO3: T-N = 130 K). The transition is characterized by a sharp kink in the magnetic susceptibility at T-N below which it continues to increase due to the frustration on the triangular lattice. The specific heat shows one clear continuous phase transition at T-N, which is independent of external magnetic field up to 9 T with an entropy content as expected for Mn3+ ions. The temperature-dependent dielectric constant displays a distinct anomaly at T-N.