Electronic structure of BiFeO3 in the presence of strong electronic correlations

Abstract

Using density-functional dynamical mean-field theory (DFDMFT) we show the importance of multiorbital electronic correlations in determining the insulating state of BiFeO 3 , a multiferroic material with an electron band gap larger than its bare bandwidth. Within the Fe 3+ oxidation state and using realistic values for the on-site Coulomb interaction, we unveil strongly correlated key features probed in x-ray photoelectron and absorption spectra, showing good qualitative theory-experiment agreement. We explore the electronic reconstruction hidden in ferromagnetic BiFeO 3 , predicting broad orbital-and spin-polarized features at low temperatures. Our proposal for ferromagnetic BiFeO 3 is expected to be an important step to understanding the emergent correlated electronic structure of magnetoelectronic and spintronic materials with persisting ordered localized moments coexisting with Coulomb reconstructed electronic states.

Mott localization in the van der Waals crystal CrI3 : A GGA+DMFT study

“…In this work we shed light onto this problem within the GGA+DMFT approximation [25], showing that the emergent strongly correlated electronic state is caused by large dynamical transfer of spectral weight with concomitant formation of orbital-selective localized moments in CrI 3 . Similar to BiFeO 3 [26] our study highlights the importance of incorporating dynamical many-particle aspects of multiorbital (MO) electronic correlation effects within the Cr-3d orbitals to correctly derive the insulating spectra of paramagnetic CrI 3 . Likewise, here we present a self-consistent many-particle study of electronic structure calculations using the GGA+DMFT approach for CrI 3 crystal.…”

“…Before delving into the emergent Mott insulating state [22] of paramagnetic CrI 3 , it should be noted that in earlier studies the hidden correlated electronic structure of ferromagnetic crystals has been studied [26,36,37], showing why they can be semiquantitatively understood using DFT+DMFT with sizable MO correlations. Here, we extend this aspect to characterize first the electronic properties of ferromagnetic CrI 3 and its link to spin and orbital polarization.…”

Tilting and Distortion in the Multiferroic Aurivillius Phase Bi6Ti3Fe1.5Mn0.5O18

“…The ion–electron interactions were described by the projector augmented wave (PAW) methods . The exchange and correlation effects were described by the Perdew–Burke–Ernzerhof (PBE) functional of the generalized gradient approximation (GGA). , A rotationally invariant Hubbard U correction was added to the 3d states of Fe and Mn, where U = 5.5 eV was used for all Fe atoms (the typical range of U values for Fe in multiferroic BiFeO 3 is between 5 and 7 eV , ) and 3.0 eV was used for Mn atoms . The U value is not required for Ti, whose PDOS is examined in this study to theoretically rationalize the experimental EELS spectra of Ti.…”

Atomic level origin of the impact of octahedral tilting and tetragonal distortions on the functional properties of the room temperature multiferroic Bi6Ti3Fe1.5Mn0.5O18

“…The exchange and correlation effects were described by the Perdew-Burke-Ernzerhof (PBE) functional of the generalized gradient approximation (GGA) [44], [45]. A rotationally invariant Hubbard U correction was added to the 3d states of Fe and Mn, where U = 5.5 eV was used for all Fe atoms (the typical range of U values for Fe in multiferroic BiFeO3 is between 5 and 7 eV [47], [48]), and 3.0 eV was used for Mn atoms [19]. The number of valence electrons for Bi, Ti, Fe, Mn, and O is 5 (valence electron configuration: 6s 2 6p 3 ), 4 (valence electron configuration: 3d 3 4s 1 ), 8…”