Tuning the multiferroic mechanisms of TbMnO3 by epitaxial strain

Kenta Shimamoto (1) , Saumya Mukherjee (2) , Sebastian Manz (3) , Jonathan S. White (2) , Morgan Trassin (3) , Michel Kenzelmann (4) , Laurent Chapon (5) , Thomas Lippert (1, 6) , Manfred Fiebig (3) , Christof W. Schneider (1) , Christof Niedermayer (2)

1 Paul Scherrer Inst, Lab Multiscale Mat Expt, CH-5232 Villigen, Switzerland
2 LNS - Laboratory for Neutron Scattering and Imaging [Paul Scherrer Institute]
3 D-MATL - Department of Materials [ETH Zürich]
4 Paul Scherrer Inst, Lab Sci Dev & Novel Mat, CH-5232 Villigen, Switzerland
5 ILL - Institut Laue-Langevin
6 LAC - Laboratory of Inorganic Chemistry [ETH Zürich]

A current challenge in the field of magnetoelectric multiferroics is to identify systems that allow a controlled tuning of states displaying distinct magnetoelectric responses. Here we show that the multiferroic ground state of the archetypal multiferroic TbMnO3 is dramatically modified by epitaxial strain. Neutron diffraction reveals that in highly strained films the magnetic order changes from the bulk-like incommensurate bc-cycloidal structure to commensurate magnetic order. Concomitant with the modification of the magnetic ground state, optical second-harmonic generation (SHG) and electric measurements show an enormous increase of the ferroelectric polarization, and a change in its direction from along the c-to the a-axis. Our results suggest that the drastic change of multiferroic properties results from a switch of the spin-current magnetoelectric coupling in bulk TbMnO3 to symmetric magnetostriction in epitaxially-strained TbMnO3. These findings experimentally demonstrate that epitaxial strain can be used to control single-phase spin-driven multiferroic states

Domaines: Physique [physics]

Kenta Shimamoto, Saumya Mukherjee, Sebastian Manz, Jonathan S. White, Morgan Trassin, et al.. Tuning the multiferroic mechanisms of TbMnO3 by epitaxial strain. Scientific Reports, 2017, 7, 9 p. ⟨10.1038/srep44753⟩. ⟨hal-01691856⟩