title: Magnetic field induced ferroelectric to relaxor crossover in Tb(1-x)Ca(x)MnO(3).
abstract: The influence of magnetic field on the electrical properties of Tb(1-x)Ca(x)MnO(3) has been investigated by means of dielectric, polarization and neutron diffraction measurements. A field of 6 T applied along the b-axis induces a crossover from ferroelectric to relaxor behavior for the x = 0.02 compound at temperatures close to the ferroelectric transition. The mechanism of this field induced crossover involves a decrease in the coherence length of the Mn-spin-spiral structure due to increasing electron hopping rates associated with double exchange. Moreover, a large negative magnetocapacitance is observed at the freezing temperature for x = 0.05, which originates from suppression of the relaxor state and thus represents a new mechanism of magnetocapacitance.
authors.affiliation: Solid State Chemistry Laboratory, Zernike Institute for Advanced Materials, Rijksuniversiteit Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.
authors.forename: N
authors.initials: N
authors.lastname: Mufti
authors.forename: G R
authors.initials: GR
authors.lastname: Blake
authors.forename: A A
authors.initials: AA
authors.lastname: Nugroho
authors.forename: T T M
authors.initials: TT
authors.lastname: Palstra