Zero Field NMR of BiFeO₃

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.

Keywords:

• Nuclear magnetic resonance
• magnetoelectric coupling

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.