Driving Spin Excitations by Hydrostatic Pressure in BiFeO3

J. Buhot (1) , C. Toulouse (1) , Y. Gallais (1) , A. Sacuto (1) , R. de Sousa (2) , D. Wang (3) , L. Bellaiche (4, 5) , M. Bibes (6) , Alain Barthélémy (6) , A. Forget (7) , D. Colson (7) , M. Cazayous (1) , M-A. Measson (1)

1 MPQ (UMR_7162) - Laboratoire Matériaux et Phénomènes Quantiques
2 UVIC - University of Victoria [Canada]
3 Xjtu - Xi'an Jiaotong University
4 Department Physics
5 Institute for nanosciences and engineering and physics departement [University of Arkansas]
6 UMPhy CNRS/THALES - Unité mixte de physique CNRS/Thales
7 LNO - Laboratoire Nano-Magnétisme et Oxydes

Optical spectroscopy has been combined with computational and theoretical techniques to show how the spin dynamics in the model multiferroic BiFeO3 responds to the application of hydrostatic pressure and its corresponding series of structural phase transitions from R3c to the Pnma phases. As pressure increases, multiple spin excitations associated with non-collinear cycloidal magnetism collapse into two excitations, which show jump discontinuities at some of the ensuing crystal phase transitions. Effective Hamiltonian approach provides information on the electrical polarization and structural changes of the oxygen octahedra through the successive structural phases. The extracted parameters are then used in a Ginzburg-Landau model to reproduce the evolution with pressure of the spin waves excitations observed at low energy and we demonstrate that the structural phases and the magnetic anisotropy drive and control the spin excitations.

Domains: Physics [physics]

J. Buhot, C. Toulouse, Y. Gallais, A. Sacuto, R. de Sousa, et al.. Driving Spin Excitations by Hydrostatic Pressure in BiFeO3. Physical Review Letters, 2015, 115 (26), ⟨10.1103/PhysRevLett.115.267204⟩. ⟨cea-01406870⟩