Claude Ederer

Weak ferromagnetism and magnetoelectric coupling in bismuth ferrite

We analyze the coupling between the ferroelectric and magnetic order parameters in the magnetoelectric multiferroic

First-principles study of spontaneous polarization in multiferroic BiFeO 3

\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}

Effect of epitaxial strain on the spontaneous polarization of thin film ferroelectrics.

using density functional theory within the local spin density approximation (LSDA) and the

Influence of strain and oxygen vacancies on the magnetoelectric properties of multiferroic bismuth ferrite

\mathrm{LSDA}+\mathrm{U}

First principles study of the multiferroics BiFeO3, Bi2FeCrO6, and BiCrO3: Structure, polarization, and magnetic ordering temperature

method. We show that weak ferromagnetism of the Dzyaloshinskii-Moriya type occurs in this material, and we analyze the coupling between the resulting magnetization and the structural distortions. We explore the possibility of electric-field-induced magnetization reversal and show that, although it is unlikely to be realized in

Dielectric anomalies and spiral magnetic order in CoCr2O4

\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_{3}

Recent progress in first-principles studies of magnetoelectric multiferroics

, it is not in general impossible. Finally, we outline the conditions that must be fulfilled to achieve switching of the magnetization using an electric field.

Experimental and computational investigation of structure and magnetism in pyrite Co1-xFexS2: Chemical bonding and half-metallicity

The ground-state structural and electronic properties of ferroelectric BiFeO 3 are calculated using density functional theory within the local spin-density approximation sLSDAd and the LSDA+U method. The crystal structure is computed to be rhombohedral with space group R3c, and the electronic structure is found to be insulating and antiferromagnetic, both in excellent agreement with available experiments. A large ferroelectric polarization of 90‐ 100 m C/c m 2 is predicted, consistent with the large atomic displacements in the ferroelectric phase and with recent experimental reports, but differing by an order of magnitude from early experiments. One possible explanation is that the latter may have suffered from large leakage currents. However, both past and contemporary measurements are shown to be consistent with the modern theory of polarization, suggesting that the range of reported polarizations may instead correspond to distinct switching paths in structural space. Modern measurements on well-characterized bulk samples are required to confirm this interpretation.

Magnetic coupling in Co Cr 2 O 4 and Mn Cr 2 O 4 : An LSDA + U study

Epitaxial strain can substantially enhance the spontaneous polarizations and Curie temperatures of ferroelectric thin films compared to the corresponding bulk materials. In this Letter we use first principles calculations to calculate the effect of epitaxial strain on the spontaneous polarization of the ferroelectrics , , and , and the multiferroic material . We show that the epitaxial strain dependence of the polarization varies considerably for the different systems, and in some cases is, in fact, very small. We discuss possible reasons for this different behavior and show that the effect of epitaxial strain can easily be understood in terms of the piezoelectric and elastic constants of the unstrained materials. Our results provide a computational tool for the quantitative prediction of strain behavior in ferroelectric thin films.

Structural distortions and model Hamiltonian parameters: From LSDA to a tight-binding description of LaMnO3

The dependencies on strain and oxygen vacancies of the ferroelectric polarization and the weak ferromagnetic magnetization in the multiferroic material bismuth ferrite,