abstract
This study provides a comprehensive insight into the effects of controlled off-stoichiometry on the structural and multiferroic properties of the hexagonal manganite LuMn1-xO3+delta (x = 0.02; delta similar to 0), supported by neutron powder diffraction measurements confirming single phase P6(3)cm symmetry and evidencing a relevant ferromagnetic component, below T-N similar to 90 K, which breaks the archetypal geometrically frustrated antiferromagnetic state typically ascribed to LuMnO3. The perturbations in the triangular disposition of spins prompt an additional electric polarization contribution and a clear enhancement of the magnetoelectric coupling which are in good agreement with the results of first principles calculations. In addition, Raman spectroscopy, dielectric permittivity, pyroelectric current and magnetic measurements as a function of temperature point out the precursor effects of the magnetic phase transitions involving a strong coupling between spins, lattice and electric order, even above the Neel temperature.
keywords
HEXAGONAL MANGANITES; WEAK FERROMAGNETISM; LUMNO3; FERROELECTRICITY; ANOMALIES; ORIGIN
subject category
Chemistry; Physics
authors
Figueiras, FG; Karpinsky, D; Tavares, PB; Goncalves, JN; Yanez-Vilar, S; Dos Santos, AFM; Franz, A; Tovar, M; Moreira, JA; Amaral, VS
our authors
Dzmitry Karpinski (Karpinsky)
Post-doc Fellowship
Fábio Gabriel Nazário Figueiras
Post-Doc Fellowship
João Nuno Santos Gonçalves
Junior Researcher
Vitor Brás Sequeira Amaral
Full professoracknowledgements
The authors acknowledge to thank the financial support from the FCT project PTDC/FIS/10541/2008 "MULTIFOX'', F. G. F author FCT grants SFRH/BD/25011/2005 and SFRH/BPD/80663/2011, D. V. K. author FCT grant SFRH/BPD/42506/2007 and RSF grant 15-19-20038, J. N. G. author FCT grant SFRH/BPD/82059/2011; S. Y. V. author Xunta de Galicia postdoctoral grant. This work was developed within the scope of the project CICECO Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013); and through the Project PTDC/FIS-NAN/0533/2012, and by QREN, through the Project Norte-070124-FEDER-000070 Nanomateriais Multifuncionais, both financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. Part of NPD measurements used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Part of NPD measurements were supported by the European Union's Seventh Framework Programme (NMI3-II-283883).