Figueiras, F.; Karpinsky, D.; Tavares, P.; Gonçalves, J.; Yáñez-Vilar, S.; Moreira Dos Santos, A.; Franz, A.; Tovar, M.; Moreira, Jo.; Amaral, V.: Novel multiferroic state and magnetoelectric coupling enhance-ment by breaking the geometric magnetic frustration in LuMn1-xO3. Physical Chemistry Chemical Physics 19 (2017), p. 1335-1341

This study reports a comprehensive insight of the effects of controlled off-stoichiometry on the structural and multiferroic properties of the hexagonal manganite LuMn1-xO3+δ (x = 0.02; δ ~0), supported by neutron powder diffraction measurements confirming single phase P63cm symmetry and evidencing a relevant ferromagnetic component, below TN ~90K, which breaks the archetypal geometrical frustrated antiferromagnetic state typically ascribed to LuMnO3. The perturbations in the triangular disposition of spins prompts an additional electric polarization contribution and a clear enhancement of the magnetoelectric coupling which are in good agreement with results of first principle calculations. In addition, Raman spectroscopy, dielectric permittivity, pyroelectric current and magnetic measurements as 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 Néel temperature.