resumo
Potential ferroelectricity in charge-transfer organic materials is often masked by the intrinsic conductivity. Here, we report the compelling evidence of ferroelectricity in organic pi-conjugated meta-nitroaniline (m-NA) crystals as shown by the local electromechanical measurements using the piezoresponse force microscopy (PFM) technique. m-NA is a charge-transfer molecular material with the exceptional optical non-linearity and perceptible conductivity along the crystallographic polar axis. While standard Sawyer-Tower measurements revealed an apparently lossy-dielectric hysteresis, The PFM switching spectroscopy indicated clear ferroelectric behaviour in this technologically important multifunctional material. Further study of the pyroelectric properties in m-NA crystals confirmed their high spontaneous polarization of 18 mu C/cm(2) at room temperature, comparable to the best known organic ferroelectrics. Published by AIP Publishing.
palavras-chave
PIEZORESPONSE FORCE MICROSCOPY; MOLECULAR-CRYSTALS; THIN-FILMS; GLYCINE; MORPHOLOGY; MNA
categoria
Physics
autores
Isakov, D; Vasilev, S; Gomes, ED; Almeida, B; Shur, VY; Kholkin, AL
nossos autores
Andrei Kholkin
Investigador Jubiladoagradecimentos
This work was supported by the European Regional Development Fund (ERDF) through Programa Operacional Factores de Competitividade (COMPETE: FCOMP-01-0124-RIDER-014628, FCOMP-01-0124-FEDER-009457)and FCT Grant No. PTDC/CTMNAN/114269/2009), Pest-C/CTM/LA0011/013, and by RFBR Grant No. 13-02-90925. 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, and by Government of the RF (Act 211, Agreement 02.A03.21.0006).