Theoretical study of static and dynamic properties of orthorhombic multiferroic substances

Wesselinowa, J. M.; Georgiev, Ivan T.

doi:10.1002/pssb.200844019

Cited by 12 publications

(7 citation statements)

References 24 publications

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“…(4) must be modified. In GFO, similar to the orthorhombic RMnO 3 and RMn 2 O 5, 28 and in accordance to the results observed by Sun et al 13 for GFO, the leading ME interaction term is taken to be linear in the electrical dipole moment, due to the improper nature of its ferroelectricity. In a ferroelectromagnet, the difference in the dielectric constant [D ¼ ðHÞ À ð0Þ] below T C is proportional to the square of the magnetization, i.e., D $ cM 2 , where c is the ME coupling constant.…”

Section: Model and Green's Functionssupporting

confidence: 72%

Origin of the different multiferroism in BiFeO3 and GaFeO3

Bahoosh

Wesselinowa

2013

Journal of Applied Physics

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We have proposed microscopic models for describing the multiferroic properties of BiFeO 3 and GaFeO 3. It is shown that the mechanisms of the multiferroism are different. In BiFeO 3 , the magnetoelectric coupling is biquadratic, whereas in GaFeO 3 it is linear. The site disorder between Ga and Fe is a primary source of the net magnetic moment in GaFeO 3. The temperature and magnetic field dependence of the polarization is calculated in order to show that the proposed models for these two multiferroics are correct. Near the magnetic phase transition temperature T N we obtain a kink in the electric properties. V

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Section: Model and Green's Functionssupporting

confidence: 72%

Origin of the different multiferroism in BiFeO3 and GaFeO3

Bahoosh

Wesselinowa

2013

Journal of Applied Physics

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“…Since the spin of TbMn 2 O 5 is assumed to be

S = 2

the calculations of the magnetic system are performed for arbitrary spin. Following () we find the magnetization

M \equiv 〈 σ_{M} 〉

\begin{matrix} right 〈 σ_{M} 〉 & center = & left \frac{1}{N} \sum_{q} ((, (S + \frac{1}{2}) coth [((), S + \frac{1}{2}) β E_{M} (boldq)]) \\ right & center & left - (), 1 / 2 coth \frac{β E_{M} false(q false)}{2}) . \end{matrix}

The analysis of the ferroelectric subsystem is more complex. One needs a matrix Green's function defined by

(\begin{matrix} 〈 〈 b_{l}; b_{m}^{†} 〉 〉 & 〈 〈 b_{l}; b_{m} 〉 〉 \\ 〈 〈 b_{l}^{†}; b_{m}^{†} 〉 〉 & 〈 〈 b_{l}^{†}; b_{m} 〉 〉 \end{matrix}) \equiv (\begin{matrix} G_{lm}^{false(f false) 11} & G_{lm}^{false(f false) 12} \\ G_{lm}^{false(f false) 21} & G_{lm}^{false(f false) 22} \end{matrix}) .

The related equations of motion for the Green's function matrix and the results are given in the appendix.…”

Section: The Modelmentioning

confidence: 74%

“…Since the spin of TbMn 2 O 5 is assumed to be S = 2 the calculations of the magnetic system are performed for arbitrary spin. Following [35] we find the magnetization M ≡ σ M :…”

Section: Papermentioning

confidence: 99%

Microscopic approach to the magnetoelectric effect in R Mn₂ O₅

Bahoosh

Wesselinowa

Trimper

2013

Phys. Status Solidi B

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The multiferroic behavior of rare‐earth manganites is studied within a microscopic model including a symmetry‐allowed magnetoelectric coupling between polarization and magnetization. The magnetic subsystem is described by a frustrated Heisenberg spin model, whereas the ferroelectric subsystem is characterized by an Ising model in a transverse field. Using Green's function method we find analytically the temperature and wave vector dependent elementary excitation of the magnetoelectric system, the polarization and the magnetization for different magnetoelectric coupling strengths. The system undergoes a magnetic transition at TN and a further reduction of the temperature leads to a ferroelectric transition at TC

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“…While calculations published in the last few years go beyond Landau theory [9,10,11,12], they fail to identify this effect.…”

Section: Introductionmentioning

confidence: 99%