Comprehensive study on ferroelectricity induced by a proper-screw-type magnetic ordering in multiferroic CuFeO2: Nonmagnetic impurity effect on magnetic and ferroelectric order

T. Nakajima, S. Mitsuda, K. Takahashi, M. Yamano, K. Masuda, H. Yamazaki, K. Prokes, K. Kiefer, S. Gerischer, N. Terada, H. Kitazawa, M. Matsuda, K. Kakurai, H. Kimura, Y. Noda, M. Soda, M. Matsuura, K. Hirota

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Abstract

We refined the magnetic structure of a ferroelectric (FE) phase of multiferroic CuFe1-x Gax O2 with x=0.035 by complementary use of spherical neutron polarimetry and a four-circle neutron-diffraction measurement, revealing that the proper-screw-type magnetic structure in the ferroelectric phase has a finite ellipticity of ∼0.9. By means of polarized neutron-diffraction and in-situ pyroelectric measurements, we also investigated the quantitative relationship between the macroscopic ferroelectric polarization (P) and the asymmetry in volume fractions with left-handed and right-handed helical magnetic order in CuFe1-x Alx O2 with x=0.0155 and CuFe1-x Gax O2 with x=0.035. These measurements revealed that the substitution of a small amount of nonmagnetic Ga3+ or Al3+ ions does not significantly change the magnitude of the local ferroelectric polarization but does reduce the sensitivity of P to the poling electric field (Ep). This implies that the mobility of the magnetic domain walls, which is sensitive to magnetic defects due to nonmagnetic substitution, determines the sensitivity of P to Ep because of a one-to-one correspondence between the magnetic and ferroelectric domains.

Original languageEnglish
Article number214423
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume79
Issue number21
DOIs
StatePublished - Jun 16 2009
Externally publishedYes

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