Theory of Spin-Orbit Enhanced Electric-Field Control of Magnetism in MultiferroicBiFeO3

Abstract

We present a microscopic theory that shows the importance of spin-orbit coupling in perovskite compounds with heavy ions. In BiFeO3 (BFO) the spin-orbit coupling at the bismuth ion sites results in a special kind of magnetic anisotropy that is linear in the applied E field. This interaction can convert the cycloid ground state into a homogeneous antiferromagnet, with a weak ferromagnetic moment whose orientation can be controlled by the E-field direction. Remarkably, the E-field control of magnetism occurs without poling the ferroelectric moment, providing a pathway for reduced energy dissipation in spin-based devices made of insulators.

Spin-induced polarizations and nonreciprocal directional dichroism of the room-temperature multiferroicBiFeO3

“…which agrees with the first ANI-induced polarization proposed by deSousa et al [48]. An additional perpendicular polarization…”

Mössbauer and magnetization studies of magnetic phase transitions in 0.5BiFeO3–0.5NaNbO3 and 0.5LaFeO3–0.5NaNbO3 solid solutions

“…5). This dramatic difference is similar to the difference in T M values of PbFe 1=2 Nb 1=2 O 3 ð …150 K) and its lead-free counterparts A 2þ Fe 1=2 Nb 1=2 O 3 ðA ¼ Ca, Sr, Ba) ( …20 K) 35,36 and seems to be due to additional contribution of the superexchange between Fe 3þ ions via the empty 6p-states of Bi 3þ to the overall superexchange in accordance with predictions of De Sousa et al 38 The absence of the MðTÞ anomaly at around 150 K for 0.5NaNbO 3 -0.5BiFeO 3 composition seems to be due to the strong diffusion of this anomaly. Similar "disappearance" of the MðTÞ anomaly corresponding to antiferromagnetic phase transition was observed, e.g., for some compositions of the PbFe 2=3 W 1=3 O 3 -PbTiO 3 , BiFeO 3 -PbTiO 3 and PbFe 1=2 Nb 1=2 O 3 -PbTiO 3 solid solutions.…”

“…M€ ossbauer studies have shown that while for 0.5BiFeO 3 -0.5NaNbO 3 the T M value is about 150 K, for 0.5LaFeO 3 -0.5NaNbO 3 it is only …25 K. Similar large difference in T M values is known for lead-containing PbFe 1=2 Nb 1=2 O 3 ð …150 K) and its lead-free counterparts A 2þ Fe 1=2 Nb 1=2 O 3 ðA ¼ Ca, Sr, Ba) ( …20 K) and is ascribed to the magnetic superexchange between Fe 3þ ions via the empty 6p-states of Pb 2þ ions. 35,36 Thus, the results obtained for 0.5BiFeO 3 -0.5NaNbO 3 and 0.5LaFeO 3 -0.5NaNbO 3 seem to be an experimental evidence of the magnetic superexchange between Fe 3þ ions in BiFeO 3 via the empty 6p-states of Bi 3þ ions theoretically predicted by De Sousa et al 38…”

“…37 Recently, a possibility of similar nontrivial magnetic superexchange between Fe 3þ ions in BiFeO 3 via the empty 6p-states of Bi 3þ was predicted theoretically. 38 However, this mechanism of superexchange seems to become noticeable only at high enough dilution of the Fe-sublattice, i.e., in solid solutions.…”

Electronic structure and optical responses of nanocrystalline BiGaO3 films: A combination study of experiment and theory

“…[1][2][3][4][5] As promising oxides, BiAlO 3 and BiGaO 3 are predicted that they should be high performance piezoelectrics and ferroelectrics with large spontaneous polarization from the hypothetical perovskite structure. 6 Experimentally, bulk perovskite-like BiAlO 3 and pyroxene-like BiGaO 3 have been synthesized using a high-pressure and high-temperature technique and their structure parameters were refined.…”