Neutron Scattering Studies of the Ferroelectric Distortion and Spin Dynamics in the Type-1 Multiferroic Perovskite Sr0.56Ba0.44MnO3

Published

October 9, 2014

Author(s)

Daniel K. Pratt, Jeffrey W. Lynn, James Mais, Omar Chmaissem, Dennis E. Brown, Stanislaw Kolesnik, Bogdan Dabrowski

Abstract

The magnetic order, spin dynamics, and crystal structure of the multiferroic Sr_0.56Ba_0.44MnO₃ have been investigated using neutron and x-ray scattering. Ferroelectricity develops at T_c=305 K with a polarization of 4.2 υC/cm² associated with the displacements of the Mn ions, while the Mn⁴⁺ spins order below I]T_N approximately equal} 200 K into a simple G-type commensurate magnetic structure. Below T_N the ferroelectric order decreases dramatically demonstrating that the two order parameters are strongly coupled. The ground state spin dynamics are characterized by a spin gap of 4.6(5) meV and the magnon density of states peaking at 43 meV. Detailed spin wave simulations with a gap and isotropic exchange of J=4.8(2) meV describe the excitation spectrum well. Above T_N strong spin correlations coexist with robust ferroelectric order.

Citation

Physical Review B

Volume

90

Issue

14

Pub Type

Journals

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Keywords

Multiferroic, Ferroelectric Order, Magnetic Order, Spin Dynamics, Neutron Scattering, Magnon Density of States

Citation

Pratt, D. , Lynn, J. , Mais, J. , Chmaissem, O. , Brown, D. , Kolesnik, S. and Dabrowski, B. (2014), Neutron Scattering Studies of the Ferroelectric Distortion and Spin Dynamics in the Type-1 Multiferroic Perovskite Sr_0.56Ba_0.44MnO₃, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=916281 (Accessed December 3, 2024)