Enhanced ferromagnetism in mechanically exfoliated CVD-carbon films prepared by using adamantane as precursor

Abstract

In this work, room-temperature ferromagnetism, which is not caused by conventional magnetic elements (e.g., Fe, Co, and Ni), is observed in carbon films prepared by using adamantane (C10H16): the smallest member of the so called diamondoid series (nano-diamond structures). These chemical-vapor-deposition films exhibit a moderately strong ferromagnetism which can be further enhanced by mechanically exfoliating the top layers of the films off; the saturated magnetization can be as large as 4.4 emu/cm3 at room temperature. Magnetic force microscopy measurements show a clear contrast in magnetization between the original and exfoliated regions, indicating that the magnetic origin likely comes from the broken “dangling” bonds at the exfoliated surface. This work suggests an inexpensive method for creating carbon films whose magnetization can be activated from mechanical exfoliation.