Ferromagnetic hysteresis and structural recrystallization in turbostratic graphite. (28th August 2019)

• Record Type: Journal Article
• Authors: Fayazi, Mahsa; Liu, Bingyan; Lei, Li; Shuai, Gao; Odunmbaku, Omololu; Wang, Shanling; He, Yi; Boi, Filippo S
• Is Part Of: Materials research express. Volume 6:Number 10(2019)
• Publication Date: 2019-08-28
• Subjects: ferromagnetism -- graphite -- defects -- turbostratic stacking; Materials science -- Research -- Periodicals; Materials science -- Periodicals; 620.11
• DOI: 10.1088/2053-1591/ab3abe
• Languages: English
• ISSNs: 2053-1591

Abstract

Abstract: The recent observation of controllable ferromagnetic and superconductive features in highly oriented pyrolytic graphite (HOPG) has attracted significant attention towards application of ferromagnetic carbon materials in data recording and computing technology. In this work we report the observation of ferromagnetic ordering in two turbostratic graphite samples by employing in situ T-XRD, VSM, EDX, T-EPR and Raman Spectroscopy. Existence of room temperature ferromagnetic hysteresis in both the analyzed samples is shown. As indicated by complementary (1) SEM/EDX (2) T-EPR and (3) Raman Spectroscopy analyses, these signals appear to be induced by the defect sites in the samples. However a possible role of the turbostratic arrangement of the carbon layers in this effect can not be excluded. By employing Rietveld refinements and T-XRD we have also investigated the changes in the structure of the turbostratic graphite phase with the increase of the temperature from 298 K to 673 K. Magnetometry was further employed to investigate the magnetic ordering in the graphitic structure of pre-annealed and post-annealed samples.