High magnetic field phase diagram of multiferroic DyMn2O5 up to 45 T

Strong magnetoelectric coupling in multiferroic crystals such as ReMn$_{2}$O$_{5}$ (Re=rare earth) has provided unprecedented opportunity to manipulate ferroelectric (FE) polarization using magnetic fields. Most of investigations to dates have yet been limited to a rather low magnetic field region. Herein, we present the first high magnetic field (B) versus temperature phase diagram of DyMn2O5 in magnetic fields up to 45 T and temperatures below 50 K, determined from the dielectric constant, pyroelectric, and magnetoelectric current measurements using various magnets; superconducting magnets up to 17 T, a dc resistive magnet up to 33 T, and a mid-pulse magnet up to 45 T. Our phase diagram reveals that at least 4 different kinds of FE domains, which show strong temperature-and field-history-dependence, develop at low temperatures below 40 K, and exhibit dramatic evolution under B. For example, as B increases at 4 K, FE polarization shows successive flopping at B~2, 7 T and 22 T, producing large dielectric constant changes, $\Delta$$\epsilon$(B)/$\epsilon$(0T) $\sim$5, 70, 20 \%, respectively. We discuss the complex phase diagram in the context of strong spin- lattice coupling that is linked to the exchange interaction between Dy f- and Mn d-spins.