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Resumen: We here revisit the electrical properties of LuFe2O4, compound candidate for exhibiting multiferroicity. Measurements of dc electrical resistivity as a function of temperature, electric-field polarization measurements at low temperatures with and without magnetic field, and complex impedance as a function of both frequency and temperature were carried out in a LuFe2O4 single crystal, perpendicular and parallel to the hexagonal c axis, and in several ceramic polycrystalline samples. Resistivity measurements reveal that this material is a highly anisotropic semiconductor, being about two orders of magnitude more resistive along the c axis. The temperature dependence of the resistivity indicates a change in the conduction mechanism at TCO ˜ 320 K from thermal activation above TCO to variable range hopping below TCO. The resistivity values at room temperature are relatively small and are below 5000 O¿cm for all samples but we carried out polarization measurements at sufficiently low temperatures, showing that electric-field polarization curves are a straight line as expected for a paraelectric or antiferroelectric material. Furthermore, no differences are found in the polarization curves when a magnetic field is applied either parallel or perpendicular to the electric field. The analysis of the complex impedance data corroborates that the claimed colossal dielectric constant is a spurious effect mainly derived from the capacitance of the electrical contacts. Therefore, our data unequivocally evidence that LuFe2O4 is not ferroelectric.
Idioma: Inglés
DOI: 10.1103/PhysRevB.88.085130
Año: 2013
Publicado en: Physical Review B 88, 8 (2013), 085130 [7 pp]
ISSN: 1098-0121
Factor impacto JCR: 3.664 (2013)
Categ. JCR: PHYSICS, CONDENSED MATTER rank: 14 / 67 = 0.209 (2013) - Q1 - T1
Financiación: info:eu-repo/grantAgreement/ES/DGA/CAMRADS
Financiación: info:eu-repo/grantAgreement/ES/MINECO/MAT2012-38213-C02-01
Tipo y forma: Artículo (Versión definitiva)
Área (Departamento): Área Física Materia Condensada (Dpto. Física Materia Condensa.)

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