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Magnetismus Vortrag: Fr., 11:30–11:50 F-V67
Melting of magneto-electric state in TbMnO3 with c−axis aligned magnetic
field
Dimitri Argyriou 1 , N. Aliouane 1 , J. Strempfer 2 , I. Zegkinoglou 2 , M. v.
Zimmermann 3
1 Hahn-Meitner-Institut, Glienicker Str. 100, Berlin D-14109, Germany – 2 Max-Planck-
Institut für Festkörperforschung, Heisenbergstraße 1, 70569,Stuttgart, Germany –
3 HASYLAB at DESY, Notkestr. 85, 22065 Hamburg, Germany
TbMnO3 is an example of a multiferroic materials where magnetism and ferroelectricity
are strongly coupled. This particular material exhibits a novel flop of the electric
polarization P from from P || c to P || a with magnetic field when field is applied
parallel to the a− or b−axis. Recently it was shown that as TbMnO3 is cooled in
a ∼10 Tesla magnetic field aligned along the c−axis, the ferroelectric phase (P || c)
exhibits a reiterant behavior, with a paraelectric phase appearing at intermediate temperatures.[1]
We have performed in-field neutron and X-ray diffraction measurements
on a TbMnO3 single crystal and find that an applied field parallel to the c−axis destabilizes
the incommensurate magnetic modulation of Mn-spins in preference of a simple
commensurate antiferromagnetic ordering (see fig. 1). The reiterant behavior of the
ferroelectric state arises from the magneto-structural coupling of Tb-spins as they order
incommensurately. [1] T. Kimura et. al., Phys. Rev. B 71, 224425 (2005).
Fig. 1: Scans along (1,k,0)
as a function of temperature
from a TbMnO3 single crystal
cooled in a H || c=12T
magnetic field. The incommensurate
reflections due to
Mn ordering are labeled as
q Mn , while incommensurate
reflections from Tb spin ordering
are labeled as q T b .
The commensurate (010) reflection
is also indicated. The
data shows that the disapperance
of the q Mn reflections
coincides with the melting of
the ferroelectric phase, while
the ordering of Tb spins at
lower temperature with its reiterant
behavior.