Probing multiferroicity and spin-spin interactions via dielectric measurements on Y-doped HoMnO$_{3}$ in high magnetic fields

摘要

The magnetic field dependent phase diagram of the ferroelectric material${\rm Ho}_{1-x}Y_{x}MnO_{3}$ has been investigated for x = 0, 0.6, and 0.8 forfields directed along both the ab in-plane and c-axis basal plane directions.Dielectric measurements are used to map out the re-entrant temperature-magneticfield phase transitions which involve in-plane Mn spin rotations in theantiferromagnetic state below the N$\acute{e}$el temperature. We show throughthe alloy study that the Ho sublattice plays a major role in all transitions,and that the phase diagram for $Ho_{1-x}Y_{x}MnO_{3}$ is dependent on magneticfield direction. We describe this behavior in terms of the interaction of theHo sublattice spin system with the underlying, robust $YMnO_{3}$antiferromagnetic triangular lattice, where the Ho-Y spin interactions arehighly sensitive to concentration and field direction.