Open AccessPercolative magnetic correlation and competing-antiferromagnetism in highly oriented pyrolytic graphite with hexagonal Moiré superlattices at the magic-angle
Author(s) -
Filippo S. Boi,
Shuai Gao,
Yi He,
Shanling Wang
Publication year - 2020
Publication title -
materials research express
Language(s) - English
Resource type - Journals
ISSN - 2053-1591
DOI - 10.1088/2053-1591/abcdd8
Subject(s) - materials science , antiferromagnetism , ferromagnetism , condensed matter physics , superlattice , highly oriented pyrolytic graphite , magnetization , raman spectroscopy , pyrolytic carbon , spintronics , magnetic field , nanotechnology , optics , physics , scanning tunneling microscope , chemistry , optoelectronics , quantum mechanics , organic chemistry , pyrolysis
Occurrence of magnetic-correlation-phenomena in multi-layered carbon-materials has recently attracted an important attention for applications in magnetic devices and spintronics. In this study, exfoliated highly-oriented-pyrolytic-graphite (HOPG) lamellae exhibiting hexagonal-Moiré-superlattices, with periodicity of ∼13 nm (1st category, θ rot ∼ 1.09° ) and ∼36 nm (2nd category, θ rot ∼ 0.39°) were investigated. Raman-spectroscopy evidenced weak D, D’ and intense G bands. In 1st category, magnetization versus field, ZFC- FC magnetic-curves from 2 K to 300 K and T-ESR revealed presence of uncorrelated and correlated ferromagnetic clusters at T* ∼ 150 K together with a critical transition at T c ∼ 50 K, compatible with percolative-ferromagnetic-correlation. Comparative measurements on the 2nd category, revealed an analogue trend, with at T* ∼ 50–60 K together with an irreversibility at T c ∼ 40 K, indicative of competing ferromagnetic/antiferromagnetic-correlations.