Co-doped manganite/graphene as new prototype for magnetic field sensor application

Abstract

Co-doped La1-xSrxMnyO3manganitewith single or few layer grapheneis a novel system designed for magnetic sensor applicationat room temperature.Manganite/graphene structurecombines the properties of manganite with negative magnetoresistance (MR) and two-dimensional graphene with positive MR in orderto increase the sensitivityofsensor based on magnetoresistence alsoin the presence of lowmagnetic field, in the range 0.1-21 T.The properties of Co-doped La1-xSrxMnyO3with single layer graphene SLG, three-layer 3LG or five layer 5LG,were characterized by using X-ray photoemission spectroscopy (XPS) and Auger electronspectroscopy(XAES).XPS studieswerefocused on the analysis of photoemissionC1sspectraof graphene layer, whereastheAugerspectra ofCKVVregion were used fordetermination of the D parameter[1].Because thisprototypeof newdevicewasprepared by exfoliatingcommercial high-quality monolayer grapheneon Cupreviously passivatedwith polymethylmethacrylate PMMA, fromthe component analysis of C1s spectrawaspossible to identify alsothe presence of polymer residues whichcould negatively affect the sensitivity to the magnetic field.Magnetoresistance measurementsofthesensors assembled with single and few layer graphene in permanent and pulsed magnetic fieldshaveshown that the best sensitivity responseis obtained for3LGsamples.This result was in accordance withXPS and XAES data,whichrevealedabetterquality of 3L graphene with lower contentof residuesdue to exfoliation process.