abstract
Isolated nonmagnetic substitutional defect ions experience huge coupled electric magnetic interaction in the single-phase multiferroic BiFeO3. In the ferroelectric state above the magnetic Ned temperature T-N, the electric environment generates a single symmetric electric field gradient (EFG) parallel to the electric polarization direction. Below T-N, a distinct magnetic interaction arises, monitored by the probe nuclei via their magnetic moment. Two magnetic environments arise, given by the relative angle of the local magnetic moment within its easy magnetic plane with respect to the EFG orientation. The angle between field gradient orientation and magnetic field direction is the most stable fitting parameter. The magnetic interaction concomitantly increases the EFG dramatically which reflects an outstandingly large local magnetoelectric coupling. In the set of best fits, two different electric environments form concurrently with two distinctly different local magnetic fields. The magnetic ordering in BiFeO3 thus completely distorts the electric environment of the nonmagnetic probe nucleus. The implications for the local effect of dopants in BiFeO3 are discussed. A third probe environment arising independent of temperature is identified and associated with an iron vacancy.
keywords
ROOM-TEMPERATURE; STRUCTURAL-PROPERTIES; ELECTRIC QUADRUPOLE; MAGNETIC-PROPERTIES; PHASE-TRANSITIONS; BIFEO3; CRYSTAL; SPECTROSCOPY; DEPENDENCE; MOSSBAUER
subject category
Materials Science; Physics
authors
Schell, J; Schmuck, M; Dang, TT; Goncalves, JN; Lewin, D; Castillo, ME; Shvartsman, VV; Costa, ARG; Koster, U; Vianden, R; Noll, C; Lupascu, DC
our authors
João Nuno Santos Gonçalves
Junior Researcheracknowledgements
The authors particularly acknowledge funding from the German Federal Ministry of Education and Research (BMBF) through Grant No. 05K16PGA and from Fundacao para a Ciencia e a Tecnologia (FCT) Project No. CERN-FIS-NUC0004-2015. We thank the BONIS team at HISKP, Bonn, for the successfully performed 181Hf implantations. Dr. Joao Guilherme Martins Correia is thankfully acknowledged for technical support during measurements. The authors thank Astita Dubey for helping with literature scan and discussions and Brahim Dkhil for fruitful discussions. J.S. did all measurements, initial fits, and wrote the first draft of the paper. A.R.G.C. helped with measurements. J.N.G. performed the simulations. M.S. and T.T.D. did the final fits and graphics. M.E.C. made the ceramic samples. V.V.S.,.I.E. and T.T.D. helped with data interpretation. R.V. and C.N. did the implantations at HISKP in Bonn. U.K. produced the 181Hf in Grenoble. D.C.L. wrote most of the final text and is responsible for final data interpretation.