Abstract
The zero-field 209 Bi NMR of bismuth ferrite, BiFeO 3 is studied at 4.2 K. The complicated multicomponent spectrum is related to a combination of the Zeeman interaction of 209 Bi nuclei with the local magnetic field, and of the quadrupolar coupling with spatially modulated electric field gradients (EFG) in the antiferromagnetic/ferroelectric phase of BiFeO 3 . The sinusoidal-wave modulation of the EFG is characterized by the variation of the 209Bi quadrupole interaction from 300 to 350 MHz. The microscopic mechanism of coupling between the ferroelectric and magnetic order parameters is studied using the density functional theory (DFT) calculations.
Acknowledgment
This research was supported in part by the FP6 EU project MULTICERAL N° NMP3 – CT 2006 – 032616, and by grant of Russian Fund for Basic Research (RFBR), project N° 08.03-00826.