Pressure-induced change in the magnetic ordering of TbMnO3
O. L. Makarova, I. Mirebeau, S. E. Kichanov, J. Rodriguez-Carvajal, and A. Forget, Phys. Rev. B 84 (2011) 020408(R).
We have studied TbMnO3 by high-pressure neutron diffraction up to 3.6 GPa and down to 1.5 K. The incommensurate spin structures of the Mn and Tb moments are strongly suppressed under pressure, and an E-type commensurate spin structure with (0,1/2,0)propagation vector is stabilized for the Mn moments. The Mn and Tb incommensurate orders which persist at low pressures or low temperatures are also affected, with a change of phase of the modulation between neighboring Mn chains and a reorientation of the Mn moments along the a axis. The results suggest both a change of the balance of the different Mn-Mn interactions and a strengthening of the Tb-Tb (or Tb-Mn) interactions under pressure.