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MA: Magnetismus

MA 5: Spin-Structures and Magnetic Phase Transitions I

MA 5.2: Vortrag

Montag, 27. März 2006, 10:30–10:45, HSZ 403

Magnetic field induced linear magneto-elastic coupling in multiferroic TbMnO₃ — •J. Strempfer¹, N. Aliouane², B. Bohnenbuck¹, D. Argyriou², I. Zegkinoglou¹, and M. von Zimmermann³ — ¹MPI/FKF, Heisenbergstr. 1, 70569 Stuttgart — ²HMI, Glienicker Str. 100, 14109 Berlin — ³HASYLAB/DESY, Notkestr. 85, 22605 Hamburg

The multiferroic compound TbMnO₃ was investigated in high magnetic fields up to 10T using high-energy x-ray diffraction, with the field oriented along all three crystallographic directions. Structural superlattice reflections at positions (0, δ_m, l) and (0, 2 δ_m, l) were investigated as a function of field and temperature. For H||a and H||b, a transition from incommensurate to commensurate wave vectors is observed which coincides with the polarization flop from P||c to P||a. Whereas at zero field only second order structural superlattice reflections are observed, first order superlattice reflections appear at finite fields which are linearly increasing in intensity with the applied magnetic field. This suggests that the quadratic magneto-elastic coupling breaks down with applied magnetic field and linear magneto-elastic coupling is induced.