Evolution of Ferroelectric and Antiferromagnetic Phases of TbMn2O5 Under High Magnetic Field up to 45 T

Abstract

We determine high magnetic field (B//a) vs temperature phase diagram of TbMn2O5 by measurements of dielectric constant (ϵ//b) and magnetization under static and pulsed B up to 45 T, and pyroelectric/magnetoelectric currents up to 9 T. Our results reveal that a ferroelectric (FE) transition temperature at T C = 38 K at B = 0 T changes little under B up to 33 T, while incommensurate antiferromagnetic phase, characterized as increased ϵ and negative polarization below 25 K at B = 0 T, becomes unstable above B = ∼20 T at low temperatures. Furthermore, a positive FE polarization component, coined with a Tb f-spin ordering below ∼15 K at B = 0 T, abruptly disappears with Tb f-spin reorientation under B ≤ ∼2 T. Determined phase diagram shows that both magnitude of FE polarization and ϵ value are sensitively dependent on the evolution of magnetic order parameters of both Mn-d and Tb-f spins tuned by high magnetic fields.