title: First principles study of improper ferroelectricity in TbMnO3.
abstract: We carry out a first-principles theoretical study of the magnetically induced polarization in orthorhombic TbMnO3, a prototypical material in which a cycloidal-spin structure generates an electric polarization via the spin-orbit interaction. We compute both the electronic and the lattice-mediated contributions to the polarization and find that the latter is strongly dominant. We analyze the spin-orbit induced forces and lattice displacements from both atomic and mode-decomposition viewpoints, and show that a simple model based on nearest Mn-Mn neighbor Dzyaloshinskii-Moriya interactions is not able to account fully for the results. The direction and magnitude of our computed polarization are in good agreement with experiment.
authors.affiliation: Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854-8019, USA. andreim@physics.rutgers.edu
authors.forename: Andrei
authors.initials: A
authors.lastname: Malashevich
authors.forename: David
authors.initials: D
authors.lastname: Vanderbilt