MAGNETIC AND FERROELECTRIC PROPERTIES OF DOPED MULTIFERROIC
Tb0,95Bi0,05MnO3 IN THE TEMPERATURE RANGE 4 – 295 K
,
1-
Filimonov A.V. 1*, Andreeva N.V.1, Vakhrushev S.B.1,2, Koroleva E.Y.1,2
St. Petersburg State Polytechnical University, St.-Petersburg, Russia; 2 - Ioffe Institute, St.-Petersburg,
Russia; *e-mail: [email protected]
TbMnO3 is a multiferroic with
ferroelectric and magnetic orders occur
near 30 and 40 K respectively [2]. TbMnO3
has
gigantic
magnetoelectric
and
magnetocapacitance effects, which can be
attributed to switching of the electric
polarization induced by magnetic fields [2].
Ferroelectricity in TbMnO3 is induced by
the noncollinear Mn spiral spin order with
inverse
Dzyaloshinskii–Moriya
(DM)
interaction, which is the driving force of
oxygen atom displacements [3].
BiMnO3 is a multiferroic with the
ferromagnetic and ferroelectric Curie
temperatures TC = 105 and 750–800 K,
respectively [4].
Tb0,95Bi0,05MnO3
Observed with X-ray diffraction structure of Tb0,95Bi0,05MnO3
at 90 K (a) and at 300 K (b): displacement of Tb, O1, O2 atoms
could be seen.
Magneto-capacitance of bulk Tb0.95Bi0.05MnO3 crystal
Tb0.95Bi0.05MnO3 is a solid solution of
the initial compounds TbMnO3 and BiMnO3
and at room temperature has the rhombic
perovskite structure with the space group
Pnma (62) and the cell parameters a =
5.321 Å, b = 5.858 Å, and c = 7.429 Å [1].
In the multiferroic compound, the
doping and substituting with different
types of magnetic ions could modify the
properties of the compound [5-7].
The interest to the investigations of
the solid solution of TbMnO3 and BiMnO3
is caused by the possibility to obtain the
multiferroic with close temperatures of
magnetic and ferroelectric ordering which
are higher than in TbMnO3.
Changes in Mn-O and Tb-O bond lengths with temperature in Tb0.95Bi0.05MnO3 crystal
Relying on studies of structural, magnetic and dielectric Tb0.95Bi0.05MnO3 properties the presence of the inhomogeneous state of the crystal was made.
Substitution of the bigger Bi3+ ions in Tb3+ positions causes local lattice distortions that bring to appearance of the smaller ions Mn4+ with changed valence. As a
result of the Tb0.95Bi0.05MnO3 contains both Mn3+ and Mn4+ ions, and free charge carries appear in it. Double exchange interaction results in the phase separation.
Magnetic-force and piezoresponse force microscopies investigation of Tb0.95Bi0.05MnO3 crystal in the temperature range of 8 – 30 K
Tb0.95Bi0.05MnO3 single-crystal grown by the
spontaneous crystallization technique by V.A.
Sanina and E.I. Golovenchits (from Ioffe
Institute), dimensions 2 × 1 × 0.5 mm3.
Directions of crystallographic axes were
determined by X-ray diffraction analysis using
SuperNova diffractometer (Oxford Diffraction,
UK).
a
b
Tb0.95Bi0.05MnO3 crystal orientation. The surface for
AFM measurements is pointed with the gray arrow.
c
Ferroelectric and magnetic states of the Tb0.95Bi0.05MnO3
crystal were measured using the cryogenic atomic-force
microscope AttoAFM I (Attocube Systems, Germany).
Both for magnetic and ferroelectric measurements
cantilevers with Co coating were taken. We used MAGT
cantilevers (Applied NanoStructures Inc., USA), with the
resonant frequency of 62 kHz, k constant of 3 N/m and
tip radius curvature of 40 nm
d
Results of Tb0.95Bi0.05MnO3 single crystal measurements using PFM and MFM techniques in the temperature range
of 8 – 30 K. a – topography of TBMO crystal surface; b – out-of-plane amplitude PFM ; c – ferromagnetic properties
distribution; d – intersection of ferromagnetic and ferroelectric properties distributions.
• The distribution of magnetic properties
on the TMNO surface, measured with
MFM, revealed the existence of
isolated ferromagnetic domains;
• According to the results of PFM
measurements, polar domains with
weak piezoresponse were found.
Ferroelectric domains had linear shape
with 250 nm average thickness and
length up to several microns.
• In the temperature range of 8 – 30 K
there are local ferromagnetic and longrange ferroelectric ordering in
Tb0.95Bi0.05MnO3 single crystal.
1. Golovenchits, E.I., Sanina, V.A.: Dielectric and Magnetic Properties of the Multiferroic Tb(1-x)BixMnO3: Electric Dipole Glass and Self-Organization of Charge Carries. JETP Lett., 81 (10), 509 -513, (2005). 2. Kimura, T., Goto, T., Shintani, H., Ishizaka, K., Arima, T., Tokura, Y.: Magnetic Control of Ferroelectric Polarization. Nature, vol. 426 (6), pp.
55-58 (2003). 3. Hur, N., Park, S., Sharma, P.A., Ahn, J.S., Guba, S., Cheong, S.-W.: Electric Polarization Reversal and Memory in a Multiferroic Material Induced by Magnetic Fields. Nature, vol. 392, pp. 392-395 (2004). 4. Kimura, T., Kawamoto, S., Yamada, I., Azuma, M., Takano, M., Tokura, Y.: Magnetocapacitance Effect in Multiferroic
BiMnO3. Phys. Rev. B, 67: 180401(R) (2003). 5. Cui., Y.: Decrease of Loss in Dielectric Properties of TbMnO3 by Adding TiO2. Physica B: Condensed Matter, vol. 403 (18), pp. 2963-2966 (2008). 6. Yang, C.C., Chung, M.K., Li, W.-H., Chan, T.S., Liu, R.S., Lien, Y.H., Huang, C.Y., Chan, Y.Y., Yao, Y.D., Lynn, J.W.: Magnetic Instability and Oxigen Defiency
in Na-doped TbMnO3. Phys. Rev. B., 74, 094409 (2006). 7. Mufti, N., Nugroho, A.A., Blake, G.R., Palstra, T.T.M.: Relaxor Ferroelectric Behaviour in Ca-doped TbMnO3. Phys. Rev. B., 78, 024109 (2008).