Relationship between hydrogen content and magnetic properties of diamondlike carbon produced by the rf plasma-enhanced chemical vapor deposition method

Diamondlike carbon (DLC) films were prepared by the rf plasma-enhanced chemical vapor deposition method. The DLC films exhibited ferromagnetic behavior when prepared at 500 W, but diamagnetic behavior when prepared at 900 W. Electron spin resonance studies revealed that the spin density of the ferromagnetic specimen was much higher than that of the diamagnetic specimen. Although no significant difference was found in Raman and x-ray photoelectron spectroscopy studies, a difference in hydrogen content was revealed in elastic recoil detection analysis (ERDA) studies. It was found that the hydrogen content of the ferromagnetic DLC film was 30% higher than that of the diamagnetic film. The origin of the magnetization in the ferromagnetic film is therefore considered to be attributable to the difference in the hydrogen content.