Interaction of multiferroic properties and interfaces in hexagonal LuMnO3 ceramics


A study on the underlying interaction mechanisms between lattice constants, magnetic and dielectric properties with inhomogeneities or internal interfaces in hexagonal, off-stoichiometric LuMnO3 oxide is presented. By increasing Mn content the a-axis constant and volume of the unit cell, the antiferromagnetic (AFM) Neel temperature, T-N, and frustration factor of the frustrated Mn3+ trimmers in basal plane show decreasing trends. It was found that increasing the annealing time improves the properties of the lattices and progressively eliminates secondary phases for compositions within the solid solution stability limits. A magnetic contribution below TN is observed for all samples. Two regimes of magnetization below and above 45 K were observed in the AFM state. The magnetic contribution below TN is assigned to either the secondary phase or internal interfaces like ferroelectric (FE) domain walls. Magneto-dielectric coupling at TN is preserved in off-stoichiometric ceramics. The presence of a low temperature anomaly of the dielectric constant is correlated to the composition of the solid solution in off-stoichiometric ceramics. Large FE domains are observed in piezoresponse force microscopy (PFM) images of doped and un-doped ceramics, whereas atomic structure analysis indicates the parallel formation of nano-sized FE domains. A combination of measured properties and microscopy images of micron-and nano-sized domains ascertain the role of lattice distortion and stability of solid solution on multiferroic properties.






Baghizadeh, A; Vieira, JM; Stroppa, DG; Vaghefi, PM; Graca, MP; Amaral, JS; Willinger, MG; Amaral, VS

nossos autores


AB acknowledges the FCT fellowship SFRH/BPD/80663/2011 and Electron Microscopy Group in Fritz Haber Institute, Berlin for giving access to the microscope for the EELS analysis. AB acknowledges Achim Klein-Hoffmann for assisting in the TEM sample preparation. We acknowledge the FCT project REDE/1509/RME/2005 in order to access all microscopes in pole of electron microscopy in Aveiro University. 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), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement

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