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  Aliouane, N.; Argyriou, D.N.; Strempfer, J.; Zegkinoglou, I.; Landsgesell, S.; Zimmermann, M. v.: Field-induced linear magnetoelastic coupling in multiferroic TbMnO₃. Physical Review B 73 (2006), p. 020102/1-4

10.1103/PhysRevB.73.020102

Abstract:
We have used in-field neutron and X-ray single crystal diffraction to measure the incommensu- rability ? of the crystal and magnetic structure of multiferroic TbMnO3 . We show that the flop in the electric polarization at the critical field HC , for field H along the a ? and b?axis coincides with a 1st order transition to a commensurate phase with propagation vector ? = (0, 1 4 , 0). In-field X-ray diffraction measurements show that the quadratic magneto-elastic coupling breaks down with applied field as shown by the observation of the 1st harmonic lattice reflections above and below HC . This indicates that magnetic field induces a linear magneto-elastic coupling.