Multi-characterization of electron-induced defects in highly oriented pyrolytic graphite

N. BAJALES; M. ÁVILA; V. GALVÁN; P. G. BERCOFF

CURRENT APPLIED PHYSICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 16 p. 421 - 427

1567-1739

Engineering the properties of materials throughdefects is at the forefront of research in Materials Science. Here, weinvestigate the defects produced on highly oriented pyrolytic graphite (HOPG)samples irradiated with 25 keV electrons at different doses. Our samples arecharacterized using micro-Raman spectroscopy, small angle X-ray scattering andatomic force microscopy measurements. We assign the D mode appearance in Ramanspectra to defect-like features, which induce distortions in the electronic density of HOPG after electronirradiation. These defect-like structures are interpreted in terms of a phenomenologicalmodel previously proposed by other authors. Furthermore, magnetic measurementsallow to follow the changes in the magnetization of electron-irradiated HOPG.Our results show a slight increment in coercivity in irradiated samples as wellas a large remanence and saturation enhancement in the sample with higherelectron irradiation dose. These novel results hint that a threshold dose needsto be overcome in order to observe a magnetic response in HOPG withelectron-induced defects.