J. Phys.: Condens. Matter 21 (11 November 2009) 452203 (6pp) doi: 10.1088/0953-8984/21/45/452203
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Magnetic field induced ferroelectric to relaxor crossover in
Tb1−xCaxMnO3
N Mufti1,3, G R Blake1, A A Nugroho1,2 and T T M Palstra1
1 Solid State Chemistry Laboratory, Zernike Institute for Advanced Materials,
Rijksuniversiteit Groningen, Nijenborgh 4, 9747AG Groningen,
The Netherlands
2 Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan
Ganesha 10, Bandung 40132,
Indonesia
3 Permanent address: Department of Physics, Universitas Negeri Malang,
Jalan Surabaya 6, Malang 65145,
IndonesiaAbstract.
The influence of magnetic field on the electrical properties of
Tb1−xCaxMnO3
has been investigated by means of dielectric, polarization and
neutron diffraction measurements. A field of 6 T applied along the
b-axis induces a crossover from ferroelectric to relaxor behavior for the
x = 0.02
compound at temperatures close to the ferroelectric transition. The mechanism of this field
induced crossover involves a decrease in the coherence length of the Mn-spin-spiral
structure due to increasing electron hopping rates associated with double exchange.
Moreover, a large negative magnetocapacitance is observed at the freezing temperature for
x = 0.05, which originates from suppression of the relaxor state and thus represents a new
mechanism of magnetocapacitance.
Print publication: Issue 45 (11 November 2009)Received 23 September 2009
Published 21 October 2009
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