Identification of microscopic spin-polarization coupling in the ferroelectric phase of a magnetoelectric multiferroic CuFe1-xAlxO2

Abstract

We have performed synchrotron radiation X-ray and neutron diffraction measurements on magnetoelectric multiferroic CuFe1-xAlxO2 (x=0.0155), which has a proper helical magnetic structure with incommensurate propagation wave vector in the ferroelectric phase. The present measurements revealed that the ferroelectric phase is accompanied by lattice modulation with a wave number 2q, where q is the magnetic modulation wave number. We have calculated the Fourier spectrum of the spatial modulations in the local electric polarization using a microscopic model proposed by Arima [T. Arima, J. Phys. Soc. Jpn. 76, 073702 (2007)]. Comparing the experimental results with the calculation results, we found that the origin of the 2q-lattice modulation is not conventional magnetostriction but the variation in the metal-ligand hybridization between the magnetic Fe^3+ ions and ligand O^2- ions. Combining the present results with the results of a previous polarized neutron diffraction study [Nakajima et al., Phys. Rev. B 77 052401 (2008)], we conclude that the microscopic origin of the ferroelectricity in CuFe1-xAlxO2 is the variation in the metal-ligand hybridization with spin-orbit coupling.

11 pages, 9 figures, to be published in Phys. Rev. B

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Cited by in corpus (7)

• Multiferroicity, The coupling between magnetic and polarization
• Magnons and electromagnons in a spin-lattice-coupled frustrated magnet CuFeO2 as seen via inelastic neutron scattering
• Non-Collinear Magnetic Phases of a Triangular-Lattice Antiferromagnet and Doped CuFeO${}_2$
• Control of ferroelectric polarization via uniaxial pressure in the spin-lattice-coupled multiferroic CuFe1-xGaxO2
• Spin-lattice coupling mediated multiferroicity in (ND4)2FeCl5D2O
• Spin-Driven Bond Order in a 1/5-Magnetization Plateau Phase in a Triangular Lattice Antiferromagnet CuFeO2
• Anisotropic magnetic field responses of ferroelectric polarization in a trigonal multiferroic CuFe1-xAlxO2 (x=0.015)