Dresden 2006 – scientific programme
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MA: Magnetismus
MA 5: Spin-Structures and Magnetic Phase Transitions I
MA 5.3: Talk
Monday, March 27, 2006, 10:45–11:00, HSZ 403
Phase diagram of the multiferroic GdMnO3 studied by thermal expansion and magnetostriction — •J. Baier1, D. Meier1, V. Ivanov2, A. Mukhin2, A. Balbashov3, J. Hemberger1,4, and T. Lorenz1 — 1II. Phys. Institut, University of Cologne, Germany — 2General Physics Institute, Russian Academy of Sciences, Moscow, Russia — 3Moscow Power Engineering Institute, Moscow, Russia — 4Institut f. Physik, University of Augsburg, Germany
Recently, the discovery of very large magnetoelectric effects in rare earth manganites RMnO3 has reopened the field of the so called multiferroic materials [1]. We present a study of the phase diagram of multiferroic GdMnO3 by thermal expansion α(T,H) and magnetostriction є(H,T). GdMnO3 shows an incommensurate antiferromagnetic order (ICAFM) below TN≃ 43 K. Further decrease of temperature leads to a canted A-type antiferromagnetic ordering (cAFM) below Tlock≃ 23 K. Above a critical magnetic field along the b direction ferroelectric order (FE, P||a) emerges below Tc≃ 10 K [1]. In zero magnetic field, we already observe an anomalous and anisotropic thermal expansion, but upon applying a magnetic field, very strong, new anomalies arise at the cAFM and ferroelectric phase boundary. Both phase transitions are of first-order type and display a very strong hysteresis. Furthermore we observe a down-bending of the ICAFM-to-cAFM boundary (Tlock) at low magnetic fields.
[1] T. Kimura et al., Nature 426, 55 (2003), T. Kimura et al., PRB 71, 224425 (2005)
Supported by the DFG through SFB 608